ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Traditional Poster Session • Functional MRI (Neuro)
2021 -2040 Pre-Clinical fMRI
2041 -2077 fMRI Methods
2078 -2105 Functional Connectivity Method & Applications
2106 -2139 fMRI:Bold Physiology & Multimodal Imaging

Wednesday 3 June 2015
Exhibition Hall 10:00 - 12:00

2021.   Restoring susceptibility induced MRI signal loss in rat deep brain structures at 9.4T and acquiring true whole brain scale fcMRI network
Rupeng Li1, Xiping Liu2, Jason W Sidabras11, Eric S Paulson3, Andrzej Jesmanowicz1, and James S Hyde1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, 2Dermatology, Medical College of Wisconsin, Milwaukee, WI, United States, 3Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, United States

The aural cavity magnetic susceptibility artifact leads to significant echo planar imaging, EPI, signal dropout in rat deep brain that limits acquisition of functional connectivity fcMRI data. We provide a method that restores the EPI signal in deep brain. Needle puncture introduction of a liquid-phase fluorocarbon into the middle ear allows acquisition of rat fcMRI data without signal dropout. We demonstrate that with seeds chosen from previously unavailable areas, including the amygdala and the insular cortex, we are able to acquire whole brain scale networks, including the limbic system. This tool allows EPI-based neuroscience and pharmaceutical research in rat brain using fcMRI that was previously not feasible.

2022.   Regional alterations between different anaesthesia protocols effects on the mice brain using resting-state fMRI
Tong Wu1, Joanes Grandjean2, Simone C. Bosshard3, Markus Rudin2, David Reutens3, and Tianzi Jiang1,4
1Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia, 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland,3The Centre for Advanced Imaging, The University of Queensland, Queensland, Australia, 4Brainnetome Centre, Institute of Automation, Chinese Academy of Sciences, Beijing, China

Anesthesia is an integral part of most resting-state fMRI mice studies and does not influence the brain as a whole to the same degree. This study attempts to examine intra-regional alterations in spontaneous fMRI signals induced by different anaesthesia protocols. Regional homogeneity (ReHo) is a measure of the temporal similarity of a local voxel neighborhood. We observed that medetomidine showed increased ReHo in striatum and decreased ReHo in the cortex and thalamus compared to other agents. Urethane showed increased ReHo in thalamus compared to several other agents. Global signal regression did not introduce dramatic changes to ReHo in this study.

2023.   The Constituents of Default Mode Network in Rats
Li-Ming Hsu1, Xia Liang1, Hong Gu1, Julia K. Brynildsen1, Jennifer A. Stark2, Kia Jackson3, Allison Hoffman3, Hanbing Lu1, Elliot A. Stein1, and Yihong Yang1
1Neuroimaging Research Branch, National institute on drug abuse, Baltimore, MD, United States, 2Maryland Neuroimaging Center, University of Maryland, MD, United States,3Center for Tobacco Products, FDA, MD, United States

Human default mode network (DMN) has been fractionated into subcomponents based on their functional connectivity architecture and their distinct responses to different cognitive tasks. However, the partitioning of DMN in animals is much less known. Since rodents have been widely used as translational preclinical models, a thorough understanding of the architecture, and relevant functions, of the DMN in rodents would be important for interpreting resting-state fMRI (rs-fMRI) data of rodent DMN. In this study, we investigate constituents of DMN in rats using rs-fMRI and diffusion tensor imaging (DTI), and discuss their potential functional relevancy.

2024.   Exploration of Functional Organization in Human Cervical Spinal Cord Using Resting State fMRI
Xiaojia Liu1,2, Fuqing Zhou3, Xiang Li3, Jiaolong Cui3, Mengye Lyu1,2, Adrain Tsang1,2, Iris Y Zhou1,2, Ed X Wu1,2, and Yong Hu3
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, Hong Kong, China, 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, Hong Kong, China, 3Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, Hong Kong, China

Resting state functional organization in the human cervical cord has only been scarcely explored. In this study, we investigated the resting state functional organization using a clinically relevant 3T whole body MRI scanner from 24 healthy subjects. The correlation coefficient computed from rsfMRI images between each ventral or dorsal horn of different segments was used to generate the correlation matrix. Segment C2 demonstrated stronger correlations with other segments. Segment C2 has a stronger neural activity level than other segments. Functional organization among segments was detected, which demonstrated the functional network in the human cervical cord.

2025.   Inter-hemispheric Resting State Functional Connectivity in Anesthesia Induced Unconsciousness
Yuncong Ma1, Christina Hamilton1, Pablo D. Perez1, Zhifeng Liang1, and Nanyin Zhang1
1Department of Bioengineering, The Pennsylvania State University, State College, Pennsylvania, United States

The neural mechanism underlying anesthesia-induced unconsciousness (AIU) remains elusive. In this study, we aimed to investigate the system level circuit mechanism of AIU by analyzing the inter-hemispheric resting-state functional connectivity (RSFC) at the awake state and five anesthetic depths. We used pairwise T Test to reveal the connectivity changes from awake state to various anesthesia states, and Pearson correlation to compare the inter-hemispheric RSFC with behavioral data across all AIU states.

2026.   Changes in resting state networks and biochemistry in a mouse model of inflammatory pain
Robert Becker1, Anke Tappe-Theodor2, Ainhoa Bilbao3, Rainer Spanagel3, and Wolfgang Weber-Fahr1
1Research group Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, BW, Germany, 2Pharmacological institute, Heidelberg University, Heidelberg, BW, Germany, 3Department of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim / Heidelberg University, Mannheim, BW, Germany

In a pilot rsfMRI/MRS study we investigated the effects of inflammatory pain on brain network structure in a group of 16 mice. Pain was induced by injection of Complete Freund's adjuvant (CFA). We found significant differences in local network parameters of 10 regions, mostly related with mood/stress/reward systems. The changes of local network features in these regions show their more global and less local role in the network. Furthermore quantified MR-Spectra show a trend for increased glutamate and glutamine concentrations in the prefrontal cortex of the CFA-group, which supports our working hypothesis of a hyper-glutamatergic input to the nucleus acumbens.

2027.   The Relationship between States of Consciousness and Brain Connectivity: A Potential Biomarker for Discriminable States of Consciousness
Christina Hamilton1, Yuncong Ma1, and Pablo Perez1
1Pennsylvania State University, State College, PA, United States

Consciousness is an elusive phenomenon that has remained obscure due to its lack of definition and standardization. To better understand consciousness, resting-state functional magnetic resonance imaging (rsfMRI) can be employed to investigate systems-level mechanisms of altered states of consciousness. Here we use rsfMRI to investigate functional brain connectivity at various doses of isoflurane anesthetic and correlate this with behavioral measures of anesthetic depth. We demonstrate that increases in isoflurane result in decreased connectivity at lower correlation thresholds. This relationship allows us to further characterize different states of consciousness and may provide a novel use of rsfMRI as a biomarker for various states of consciousness.

2028.   Network Modeling of mouse brain fMRI under the effect of different anesthetics
Qasim Bukhari1, Aileen Schröter1, and Markus Rudin1,2
1Institute of Biomedical Engineering, ETH and University of Zürich, Zürich, Switzerland, 2Institute of Pharmacology and Taxicology, University of Zürich, Zürich, Switzerland

In this work we have applied dual regression and network modeling using FSL Nets to the fMRI mouse data. The goal of the study was to understand network connectivity differences under the effect of different anesthesia regimens (isoflurane, propofol, urethane and medetomidine). The analysis revealed higher degree of similarity in functional networks between propofol and urethane, while isoflurane also showed similar network patterns. However medetomidine produced very different functional brain networks than other anesthesia regimens. Our study confirmed that despite the inferior signal-to-noise ratio intrinsic in mouse fMRI, it is possible to deduce significant network connectivity differences.

2029.   Contributions of spiking activity to the fMRI response in the rat olfactory bulb
Alexander John Poplawsky1, Mitsuhiro Fukuda1, and Seong-Gi Kim2,3
1Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea,3Biomedical Engineering and Biological Sciences, Sungkyunkwan University (SKKU), Suwon, Korea

The contribution of neural spiking activity to the fMRI response is not completely understood. In the current study, we directly suppressed the spiking of output neurons in the rat olfactory bulb by simultaneous stimulation of excitatory and inhibitory neural pathways and measured the resultant cerebral blood volume-weighted (CBV) fMRI changes. We found a small, but significant, CBV increase due to spiking activity, while the majority of the increase corresponded to an inseparable combination of synaptic and spiking activities. We conclude that, although synaptic activity may be the dominant source of the fMRI response, spiking activity does contribute slightly.

2030.   Near-Physiological Mouse fMRI of Nociception
Henning Matthias Reimann1, Jaroslav Marek1, Jan Hentschel1, Till Huelnhagen1, Andreas Pohlmann1, and Thoralf Niendorf1,2
1Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrueck Center for Molecular Medicine, Berlin-Buch, Berlin, Germany, 2Experimental and Clinical Research Center, Charite-Universitatsmedizin, Berlin, Germany

Chronic pain is still a major clinical issue with limited treatment options. The combination of fMRI and mouse genetics provides great potential for novel targeted drug development. Still, the potential of nociceptive mouse studies using fMRI is as yet untapped due to methodological constraints. Here we present enabling methodology, which allows near-physiological nociceptive mouse fMRI studies yielding spatially discrete BOLD effects of high magnitude for mild noxious stimuli of 46°C. This is the first report on BOLD activation patterns or BOLD effects of this significance and magnitude in mouse fMRI with thermostimulation.

2031.   Determination of sources for evoked BOLD response under Hyperbaric Oxygen
Damon Philip Cardenas1,2, Eric R Muir1,3, Shiliang Huang3, and Timothy Q Duong1,3
1University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States, 2Biomedical Engineering, University of Texas San Antonio, San Antonio, Texas, United States, 3Research Imaging Institute, San Antonio, Texas, United States

Hyperbaric oxygen (HBO) therapy is used to treat a number of ailments. Previously, during HBO at 3 atmospheres absolute fMRI studies, it was observed that BOLD response to an evoked stimulus was not “washed out” as a result of highly increased oxygen concentration. Additional experiments were performed to evaluate the potential contributions of stimulus-evoked inflow, spin density, and electrical activity to BOLD fMRI responses under HBO. CBF and BOLD fMRI of forepaw stimulation in anesthetized rats was performed under HBO and compared with normobaric air .

2032.   Etomidate: A novel anesthetic of choice for functional magnetic resonance imaging in mice
Georges Hankov*1,2, Marija M Petrinovic*1, Aileen Schroeter2, Andreas Bruns1, Markus Rudin2,3, Markus von Kienlin1, Basil Künnecke1, and Thomas Mueggler1
1Neuroscience Discovery, F. Hoffmann-La Roche Pharmaceuticals Ltd, Basel, Basel-City, Switzerland, 2Institute for Biomedical Engineering, University of Zurich and ETH, Zurich, Zurich, Switzerland, 3Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland

Functional MRI applied across different genetic mouse models of neurodevelopmental disorders holds promise to reveal pathological alteration at the neurocircuitry level and thus to aid devising novel therapies and biomarkers. Prerequisite is a reliable, non-terminal anesthesia protocol that is applicable to longitudinal studies in a broad range of mouse lines. Here, a novel anesthesia protocol based on the injectable GABAergic anesthetic etomidate has been established and validated using perfusion and BOLD fMRI. Under etomidate, basal perfusion remains in a physiological range, cerebrovascular reserve capacity is preserved and regions-specific perfusion- and BOLD changes are elicited upon pharmacological and sensory stimulation, respectively.

2033.   MEMRI and BOLD analyses of the olfactory perception system in response to odorant stimuli in mice
Hirotsugu Funatsu1, Sosuke Yoshinaga1, Haruna Goto1, Makoto Hirakane1, Shigeto Iwamoto1, and Hiroaki Terasawa1
1Department of Structural BioImaging, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan

Odors are chemical signals that regulate a wide range of social and sexual behaviors in animals. The aim of this study is to reveal the neural circuitry from the olfactory bulb to the higher-order brain areas that recognize and discriminate odors in mice. Based on the real-time BOLD and longer time-scale MEMRI techniques, the muscone odor induced signal enhancement in the peripheral olfactory bulb, where chemical signals from the olfactory epithelium are transmitted. The BOLD signal-enhanced regions coincided with the regions identified by an immunohistochemical analysis. We successfully visualized the odor-evoked activation by the combined use of BOLD and MEMRI.

2034.   Functional MRI of the main and accessory olfactory system in the whole rodent brain
Eric R. Muir1, Linlin Cong1, KC Biju2, William E. Rogers1, Robert A. Clark3, and Timothy Q. Duong1
1Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States, 2Department of Medicine, University of Texas Health Science Center, San Antonio, TX, United States, 3Institute for integration of Medicine & science and South Texas Veterans Health Care System, University of Texas Health Science Center, San Antonio, TX, United States

The olfactory system in most mammals consists of the main and the accessory olfactory systems. The main olfactory bulb receives input from the olfactory epithelium which senses volatile odors, while the accessory olfactory bulb receives input from the vomeronasal organ which senses pheromones. The accessory olfactory system plays an important role in rodents, but a single fMRI study investigating only the olfactory bulb of odor and pheromone stimulation has been performed to our knowledge. The aim of this study was to investigate fMRI responses to odor and urine (which contains pheromones) in the entire olfactory network of the mouse brain.

2035.   A reproducible experimental protocol for longitudinal rat fMRI studies: electrical mystacial pad stimulation under isoflurane anesthesia
Shin-Lei Peng1,2, Ling-Yi Huang1, Sheng-Min Huang1, Yi-Chun Wu3, Hanzhang Lu2, Fu-Chan Wei4, Chih-Jen Wen4, Hui-Yu Cheng4, Chih-Hung Lin4, and Fu-Nien Wang1
1Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, 2Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 3Molecular Imaging Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan, 4Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan

fMRI plays an role in neuroscience researches. Investigating animal fMRI studies is an essential step toward understandings of cortical reorganization after surgery. Most researches use alpha-chloralose as an anesthetic, which is improper for follow-up studies. Here, we established a new protocol of rat electric mystacial pad (MP) stimulation under isoflurane anesthesia with advantages of increased BOLD sensitivity and possibility for longitudinal studies. Results show MP stimulation exhibited reproducible activations in the sometosensory cortex. In terms of the extension of activations and induced BOLD signal changes, results from MP stimulation under isoflurane anesthesia are comparable with those under alpha-chloralose anesthesia.

2036.   Mapping the Visual Pathway in the Mouse Brain using Snapshot fMRI
Arun Niranjan1, Jack A Wells1, and Mark F Lythgoe1
1Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom

Mouse brain fMRI has made significant progress over the last 10 years, but remains technically challenging and requires further efforts to improve data acquisition. In this work we demonstrate the use of visual stimulation as a viable task for fMRI of the mouse brain, with robust responses in the mid-brain (superior colliculus, lateral geniculate nuclei), mapping the visual pathway. We also examine the use of GE-EPI with multiple snapshots (compressed segments) as a way of reducing image distortion due to B0 inhomogeneities at the point of acquisition.

2037.   How specific is specific? Stimulus-evoked fMRI in rats and mice
Giovanna Diletta Ielacqua1, Aileen Schroeter1, Mark Augath1, Felix Schlegel1, and Markus Rudin1,2
1Institute for Biomedical Engineering, ETH and University of Zurich, Zurich, Switzerland, 2Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland

Stimulus-evoked fMRI experiments in mice show widespread hemodynamic responses even to innocuous stimulation, indicating general arousal of the animal. Systemic cardiovascular responses to stimuli appear to overrule cerebral hemodynamics and mask specific stimulus-evoked responses. Measurements in rats are less confounded by such impact, resulting in predominantly contralateral activation of cortical somatosensory cortical area involved in processing of the stimulus. Here, we characterize fMRI responses in further detail and study three different paw stimulation paradigms (electrical, chemical and thermal) in rats and mice. Better understanding the interplay between specific and systemic fMRI signal contributions should help enhancing specificity in fMRI.

2038.   Functional imaging at 14.1T using high-resolution pass band bSSFP
Klaus Scheffler1, Philipp Ehses1, Yi He1, Hellmut Merkle1, and Xin Yu1
1MRC department, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, Tübingen, Germany

Sub-millimeter fMRI at very high fields with EPI is challenging due to the rapid signal decay and B0-related distortions. Balanced SSFP offers the possibility of high-resolution (100 um) acquisitions without spatial distortions and significantly higher temporal resolution compared to FLASH. Observed signal changes largely depend on T2 rather than T2* indicating a higher spatial selectivity compared to gradient echo-based methods.

2039.   T2 weighted high-resolution fMRI in human visual cortex at 9.4 T using 3D-GRASE
Valentin G. Kemper1, Federico De Martino1,2, Desmond H. Y. Tse3,4, Benedikt A. Poser1, Essa Yacoub2, and Rainer Goebel1
1Cognitive Neuroscience FPN, Maastricht University, Maastricht, Limburg, Netherlands, 2Center for Magnetic Resonance Research, CMRR, Radiology, University of Minnesota, Minneapolis, MN, United States, 3Neuropsychology and Psychopharmacology, FPN, Maastricht University, Maastricht, Limburg, Netherlands, 4Radiology, University Medical Centre, Maastricht University, Limburg, Netherlands

A zoomed, inner-volume 3D-GRASE sequence was used to acquire T2 weighted 0.8 mm and 0.6 mm isotropic resolution fMRI at 9.4 T in human early visual areas. Robust activation patterns could be observed at both resolutions. Results are compared to 7 T data of the same volunteer with the same functional paradigm and similar technical set-up. At the same resolution, temporal SNR is significantly higher at 9.4 T than at 7 T, while T2 weighted fMRI signal changes induced by a visual task were found to be similar.

2040.   BOLD-signal representation of incisional and inflammatory pain in rat brain after noxious electrical and noxious mechanical stimulation
Saeedeh Amirmohseni1, Daniel Segelcke2, Esther Pogatzki-Zahn2, and Cornelius Faber1
1Department of Clinical Radiology, University Hospital Muenster, Muenster, Germany, 2Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany

The present study investigates the BOLD-response in pain-related brain regions in an incisional and an inflammatory rat model during noxious electrical stimulation (NES) and noxious mechanical stimulation (NMS) of the injured hindpaw under the anesthesia with medetomidine. Differences in the response to NMS and NES were observed. Upon NMS, the response in the inflammation group was higher as compared to both incision and sham group. Upon NES, significantly higher responses were observed for both pain models as compared with the sham group. Different responses for the two pain models were observed in S1 and RSC.

Wednesday 3 June 2015
Exhibition Hall 10:00 - 12:00

2041.   Identify the “single unit” of neurovascular coupling by single-vessel fMRI and optogenetics
Maosen Wang1,2, Yi He1, Yaohui Tang1, Hellmut Merkle3, and Xin Yu1,2
1Research Group of Translational Neuroimaging and Neural Conteol,High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tuebingen, Baden-Wuerttemberg, Germany, 2Graduate School of Neural & Behavioural Sciences International Max Planck Research School, University of Tuebingen, Tuebingen, Baden-Wuerttemberg, Germany, 3Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Str, National Institutes of Health, Bethesda, MD, United States

It has been demonstrated that the hemodynamic signal from individual venules can be detected directly with fMRI. Here, the hemodynamic signal from BOLD and CBV fMRI was measured at high temporal(100ms) and spatial resolution(150x150µm) in layer 4/5 of the rat forepaw S1with fast gradient-echo MRI. Distinctly different voxels were activated in BOLD vs CBV fMRI. In contrast to the BOLD activated voxels primarily located at the penetrating venules, CBV activated voxels were primarily located at penetrating arterioles. This result makes it possible to directly image the CBV and BOLD response at the single-vessel level to understand neurovascular coupling.

2042.   Combined optogenetic fMRI and optical Ca2+-recordings for functional mapping of thalamo-cortical circuits in rat
Lydia Wachsmuth1, Florian Schmid1, Miriam Schwalm2, Albrecht Stroh2, and Cornelius Faber1
1Department of Clinical Radiology, University of Münster, Münster, Germany, 2Institute of Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany

We combined small animal fMRI with fiber-based optogenetic excitation of CHR2 and C1V1, transduced in rat cortex and thalamus, and with cortical fluorescence detection of a Ca2+-sensitive dye (OGB-1) in order to assess the scale of optogenetic network activation in terms of the spatial and temporal patterns of network recruitment. Onset, peak time and decay characteristics of BOLD time courses and amplitude and decay characteristic of Ca2+ responses appeared similar upon optogenetic and sensory-driven, endogenous network activation, confirming that ofMRI can serve as a model for functional mapping of brain circuits.

2043.   Impact of Anesthesia on Optogenetically Activated Medical Prefrontal Functional Network in Rats
Zhifeng Liang1,2, Glenn D.R. Waston2,3, Kevin D. Alloway2,3, Gangchea Lee1, Thomas Neuberger1, and Nanyin Zhang1,2
1Dept. of Biomedical Engineering, Pennsylvania State University, University Park, PA, United States, 2Center for Neural Engineering, The Huck Institutes of Life Sciences, Pennsylvania State University, University Park, PA, United States, 3Neural and Behavioral Sciences, College of Medicine, Pennsylvania State University, Hershey, PA, United States

It has been increasingly recognized that anesthesia has profound impacts on functional magnetic resonance imaging (fRMI) studies. Specifically, we have previously demonstrated the impact of anesthesia on global organization and local circuits in rodents using resting-state functional MRI (rs-fMRI). To further explore this impact in tas- based fMRI, we utilized optogenetics-fMRI (opto-fMRI) to examine the global impact of optically induced neural activation of infralimbic cortex in rodents. The results indicated that both the spatial extent and the amplitude of BOLD signal activation were reduced in the anesthetized state, compare to the awake state.

2044.   Selective optogenetic stimulation of VTA dopaminergic neurons enhances the neuronal representation of sensory input
Heather K. Decot1,2, Wei Gao3,4, Joshua H. Jennings1,2, Pranish A. Kantak2, Yu-Chieh Jill Kao4,5, Manasmita Das4,5, Ilana B. Witten6, Karl Deisseroth7, Yen-Yu Ian Shih4,5, and Garret D. Stuber1,2
1Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 2Departments of Psychiatry & Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 3Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 4Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 5Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 6Princeton Neuroscience Institute & Department of Psychology, Princeton University, Princeton, NJ, United States, 7Department of Bioengineering, Stanford University, Stanford, CA, United States

This project aims to investigate whether sensory representation measured with fMRI is affected by selective dopaminergic activity. We first measured changes in cerebral blood volume (CBV) signals in response to a range of forepaw stimulation frequencies. We then repeatedly paired a single forepaw stimulation frequency (9 Hz) with 30 Hz optogenetic stimulation of VTA dopaminergic neurons. Following the pairing, we re-assessed changes in CBV fMRI responses to all forepaw stimuli frequencies. We found VTA dopaminergic activity paired with forepaw stimulation enhances the neuronal representation of the sensory stimulus. These data suggest that aberrant dopaminergic signaling may degrade optimal neuronal network dynamics, which in turn may shift large-scale brain network dynamics to promote maladaptive states.

2045.   Multiband Multiecho 2D-EPI: Maximizing BOLD CNR for fMRI at 3T
E. Daniel P. Gomez1, Jenni Schulz1, Rasim Boyacioglu1, David G. Norris1,2, and Benedikt A. Poser3
1Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, Gelderland, Netherlands, 2Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany, 3Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands

Multiband Multiecho 2D-EPI with blipped-CAIPI is an MR imaging sequence that allows the acquisition of multiple slices simultaneously, thus dramatically reducing acquisition time and repetition time, and of multiple echoes with different TEs after a single RF excitation, improving BOLD sensitivity in fMRI studies. In this study we compared various MB-ME 2D EPI protocols - different in the number of slices excited simultaneously, in-plane acceleration factors and CAIPI factors - to maximize the BOLD CNR for fMRI studies.

2046.   Reduction of susceptibility artifacts and enhancement of BOLD contrast in functional MRI using multi-band multi-echo GE-EPI
Tae Kim1, Tiejun Zhao2, Yoojin Lee1, and Kyongtae Ty Bae1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Siemens Medical Solution USA, Siemens MediCare USA, PA, United States

Multiband (MB) techniques allows many thin slices in conjunction with multi-echo within a given TR normally used for conventional EPI of the whole brain. Summation of contiguous thin slices with this technique recovered signal drop-out from susceptibility artifacts and improved BOLD sensitivity from these areas. This technique can be routinely used for fMRI studies focusing on areas with high susceptibility artifacts.

2047.   Whole-brain, sub-second data collection for task-evoked fMRI studies using simultaneous multi-slice/multiband acquisition
Stephanie McMains1, R Matthew Hutchison1,2, and Ross W Mair1,3
1Center for Brain Science, Harvard University, Cambridge, MA, United States, 2Department of Psychology, Harvard University, Cambridge, MA, United States, 3AA Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States

We studied visual cortex response at a variety of slice accelerations and TR reductions to investigate the advantages and potential costs for task-based fMRI associated with parameters that allow for whole-brain, sub-second data collection with both block and event-related design paradigms. tstats were significantly higher in the block-design short-TR scans, due to the much larger number of time-points acquired. However, a significant increase is still observed after auto-regressive modeling correction, indicating benefits to block-design experiments from high temporal resolution acquisitions. The observation of higher betas in the event-related design experiment with the short-TR scans is unexpected, and perhaps indicates the hemodynamic response is captured more accurately with the higher temporal resolution.

2048.   Evaluation of multi-echo multi-band EPI with ME-ICA denoising at 7T
Sascha Brunheim1,2, Helen C. Lückmann1, Prantik Kundu3, Rainer Goebel1,2, and Benedikt A. Poser1
1Faculty of Psychology and Neuroscience, Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 2Brain Innovation B.V., Maastricht, Netherlands, 3Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institutes of Health, Bethesda, MD, United States

Multi-echo and multi-band techniques have independently and rapidly established themselves as new standards in fMRI acquisition. Bringing them together offers tremendous potential to reap the benefit of both: faster TR to better resolve confounding physiological noise such as heart beats, and the multi-echo information to then separate out these signals. We evaluate different combinations of slice- and in-plane acceleration with different numbers of echoes in conjunction with multi-echo denoising using ME-ICA.

2049.   Comparing resting state fMRI cleaning approaches using multi- and single-echo acquisitions in healthy controls and patients with ADHD
Ottavia Dipasquale1,2, Arjun Sethi3, Maria Marcella Laganà2, Francesca Baglio2, Prantik Kundu4, Giuseppe Baselli1, Neil A Harrison3, and Mara Cercignani3
1Politecnico di Milano, Milan, MI, Italy, 2IRCCS, Don Gnocchi Foundation, Milan, MI, Italy, 3Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom, 4Section on Advanced Functional Neuroimaging, Brain Imaging Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States

Artifact removal is an intrinsic challenge of resting state fMRI data, since images are acquired without experimental modulation of brain function, thus with no a-priori knowledge about the signal of interest. The aim of this study was to compare some data-driven cleaning procedures based on single- and multi-echo acquisitions. We qualitatively show the ability of the different methods to remove artifacts from a dataset that includes both typical subjects and subjects with a neuropsychiatric disorder, characterised by restlessness and high degree of head movements.

2050.   Fast, focused fMRI at high spatial resolution: 3D-EPI-CAIPI with cylindrical excitation
Wietske van der Zwaag1, Mayur Narsude2, Marzia Restuccia2, Olivier Reynaud1,3, Daniel Gallichan1, and Jose P. Marques1
1CIBM, EPFL, Lausanne, VD, Switzerland, 2LIFMET, EPFL, Lausanne, VD, Switzerland, 3Department of Radiology, Bernard and Irene Schwartz Center for Biomedical Imaging, NYU School of Medicine, New York, NY, United States

The 3D-EPI-CAIPI sequence was combined with a 2D-RF pulse to selectively image a cylindrical region of interest (such as the brainstem) with high spatial (1.5mm) and high temporal resolution (1s/volume). Use of the cylindrical excitation pulse did not reduce tSNR or BOLD sensitivity within the region of interest. This sequence allows a significant reduction of the FOV compared to full slab acquisitions, which can be used to increase spatial and/or temporal resolution and to reduce susceptibility-induced distortions, finally resulting in functional data with high spatio-temporal resolution, high anatomical fidelity and high BOLD sensitivity.

2051.   Evaluation of 2D multiband EPI imaging for high resolution, whole brain fMRI studies at 3T: sensitivity and slice leakage artifacts
Nick Todd1, Steen Moeller2, Edward J. Auerbach2, Essa Yacoub2, Guillaume Flandin1, and Nikolaus Weiskopf1
1Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom, 2Center for Magnetic Resonance Research, University of Minnesota, Minnesota, United States

This study evaluates a 2D multiband EPI sequence for 1.5mm high resolution, whole brain fMRI applications at 3T in terms of BOLD sensitivity and possible false activation due to signal leakage between the simultaneously excited slices. Ten healthy volunteers were imaged performing a visual/motor task under a 4 x 2 within-subject factorial design that considered multiband factors 1, 2, 4, and 6 (all with factor 2 in-plane GRAPPA), and reconstruction methods Slice-GRAPPA and Split Slice-GRAPPA. Results show clear gains in BOLD sensitivity for multiband factors 2, 4, and 6, manifested as a greater number of total voxels activated and higher maximum t-score values. However, signal from highly activated clusters was leaking into adjacent simultaneously excited slices and causing false positive activation at known alias locations. The effect was strongest for multiband factors 4 and 6 reconstructed with Slice-GRAPPA, but was greatly reduced using the Split Slice-GRAPPA approach.

2052.   High temporal resolution BOLD fMRI based on partial separability model with L2 norm constraint
caiyun shi1, xiaoyong zhang1,2, guoxi xie1, lijuan zhang1, chunxiang jiang1, and xin liu1
1Shenzhen Key Lab for MRI, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, shenzhen, guangdong, China, 2Centers for Biomedical Engineering, College of Information Science and Technology, University of Science and Technology of China, Hefei, China

Function magnetic resonance imaging(fMRI), which is a technique that measures the hemodynamic response realted to neural activity in the brain, requires a high spatial and temporal resolution. In this paper,we proposed a new method for accelerating fMRI experiments using sparse sampling of (k, t)-space which can greatly improve the temporal resolution than EPI. The performance of the proposed method has been evaluated using retrospective undersampling of EPI-based fMRI data and in vivo experiment. The proposed method produced accurate reconstruction of both the gray-scale images and the activation maps, and captured the BOLD signal with reduced imaging time for fMRI study.

2053.   Multi-Echo Independent Component Analysis (ME-ICA) of High Frequency Resting-State fMRI Data
Valur Olafsson1, Prantik Kundu2, and Thomas Liu3
1Neuroscience Imaging Center, University of Pittsburgh, Pittsburgh, PA, United States, 2Dept. of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, 3Center for functional MRI, UCSD, La Jolla, CA, United States

The recent emergence of fast simultaneous multi-slice functional MRI acquisitions has increased interest in exploring high frequency resting-state networks for functional connectivity MRI. Although studies have reported detecting high frequency networks, little has been done to investigate if the underlying source is truly BOLD based. Here, we propose to investigate the occurrence of whole brain high frequency BOLD resting-state networks, using multi-echo independent component analysis (ME-ICA) of high-pass filtered multi-echo simultaneous multi-slice (MESMS) data, which allows for automatic identification of high frequency BOLD and non-BOLD networks. We find that BOLD networks at frequencies higher than 0.2Hz are largely nonexistent.

2054.   Simultaneous Multislice Acquisition to Avoid Motion Artifacts in Challenging Patient Populations
Andrew S Nencka1, Andrew M Huettner2, L. Tugan Muftuler3, Kevin M. Koch1, and Rasmus Birn4
1Departments of Biophysics and Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, 3Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States, 4Department of Psychiatry, University of Wisconsin, Madison, WI, United States

Simultaneous multislice (SMS) imaging is becoming wide spread in resting state acquisitions following developments from the Human Connectome Project. While most SMS studies are focused upon increasing both spatial and temporal resolution, this study is focused primarily upon increasing volume acquisition time to effectively freeze subject motion. In cases of challenging patient populations, including unsedated children, subject motion can destroy functional connectivity measures. The goal of this work is to acquire the full brain volume as quickly as possible in a resting state acquisition that is expected to be corrupted by motion. In this case, intra-volume motion artifacts can be eliminated. Although full volume coverage with 8mm isotropic voxels can be achieved in 150 ms, data acquired over 390 ms with spatial resolution of 2.6 x 2.6 x 4 mm3 was found to sufficiently avoid intra-acquisition motion artifacts in the presence of substantial motion. This work offers a new perspective for the application of SMS acquisitions in patient populations.

2055.   Nonlinear trajectories in real-time fMRI using target volumes
Bruno Riemenschneider1, Pierre Levan1, Marco Reisert1, and Jürgen Hennig1
1University Medical Center Freiburg, Freiburg, Germany

It is shown that when restricting to a number of predefined volumes, nonlinear trajectories can be used for real-time fMRI. The average time series of the the volumes can be computed efficiently after performing pre-scan calculations. A comparison of two methods is conducted using simulated data, and exemplary time series is reconstructed using real data.

2056.   The magnitude point spread function is an inadequate measure of T2*-blurring in EPI
Laurentius Huber1, Maria Guidi1, Jozien Goense2, Toralf Mildner1, Robert Trampel1, Jessika Schulz1, Cornelius Eichner1, Robert Turner1, and Harald E Möller1
1Max Planck Institute for Human Cognitive & Brain Sciences, Leipzig, Germany, 2University of Glasgow, United Kingdom

We investigated here how the T2*-decay during k-space acquisition in EPI affects the blurring of the resulting image. We show that the corresponding PSF broadening is an inadequate measure of describing the associated T2*-blurring. Based on theoretical and experimental results shown, we conclude that full k-space acquisition GE-EPI has higher effective resolution than half k-space acquisition GE-EPI or than SE-EPI. This helps to disentangle layer-dependent activation with higher effective resolution.

2057.   nMapping: High speed, high SNR fMRI using direct mapping of functional networks
Eric Wong1
1Radiology/Psychiatry, UC San Diego, La Jolla, CA, United States

In fMRI, image acquisition and processing are typically treated as separate processes. We show here that when the goal is to obtain the functional time course of brain networks or nodes, the SNR per unit time can be dramatically increased by collecting highly under sampled data and estimating the time courses directly from raw k-space data, bypassing the formation of conventional images.

2058.   Assessment of prospective motion correction using optical tracking system for reduction of stimulus-correlated false positive activations in high spatial resolution functional magnetic resonance imaging
Ikuhiro Kida1,2, Takashi Ueguchi1,2, Yuichiro Matsuoka1,2, and Maxim Zaitsev3
1Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita, Osaka, Japan, 2Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan, 3University Medical Centre Freiburg, Freiburg, Germany

Head motion may have a negative impact on fMRI results with high spatial resolution at ultra-high magnetic field. Prospective motion correction (PMC) using external position information based on optical tracking is one of the solutions for mitigating motion-related false positive activation (FPA). We evaluated the PMC with 1 mm isotropic resolution at 7T. A great improvement of FPA for phantom study suggest that PMC using optical tracking system promises an improvement of motion-induced artifact at 1 mm isotropic resolution. In a human study only a slight improvement was observed, which suggests improvements are needed for both the present study design and possibly the PMC set-up.

2059.   Robust ACS acquisition for 3D echo planar imaging
Dimo Ivanov1, Markus Barth2, Kâmil Uludağ1, and Benedikt A Poser1
1Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 2University of Queensland, Brisbane, Australia

3D echo planar imaging (3D EPI) has become a popular fast imaging sequence with numerous applications especially at ultra-high field. Here, we investigate different ACS acquisition schemes for 3D EPI GRAPPA reconstructions and propose a robust segmentation scheme that considerably reduces residual aliasing and provides high temporal stability.

2060.   Matched-filter acquisition of high-resolution single-shot spirals
Lars Kasper1,2, Maximilian Haeberlin1, Saskia Bollmann1, S. Johanna Vannesjo1, Bertram J. Wilm1, Benjamin E. Dietrich1, Simon Gross1, Klaas E. Stephan2, and Klaas P. Pruessmann1
1Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland, 2Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland

High-resolution single-shot variable density spirals with acquisition densities matched to a Gaussian smoothing kernel are presented. Concurrent field monitoring and advanced image reconstruction (iterative SENSE and static B0-correction) proved to be instrumental to arrive at a high image quality. Matched-filter spirals increased tSNR of time series after fMRI-typical post-processing compared to Archimedean spirals and in summary, realize the best match to Gaussian smoothing kernel to date.

2061.   Interactions between Physiological Noise Correction and GRAPPA Reconstruction in EPI Data
R. Allen Waggoner1, Zhentao Zuo2, Yan Zhuo2, Topi Tanskanen1, Kenichi Ueno3, Keiji Tanaka1, and Kang Cheng1,3
1Laboratory for Cognitive Brain Mapping, RIKEN - Brain Science Institute, Wako-shi, Saitama, Japan, 2State Key Laboratory of Brain and Cognitive Science,Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 3RRC, RIKEN - Brain Science Institute, Wako-shi, Saitama, Japan

Physiological noise correction (PNC) is now commonly used to minimize the variance in fMRI data. The correction is most often performed in image space, however this methodology was originally developed as a k-space based correction. GRAPPA is widely used to accelerate data acquisition. The ACS lines are usually acquired separately, however this temporal mismatch could allow physiological noise to degrade the GRAPPA reconstruction. To explore the influence of physiological noise on GRAPPA reconstruction, we have applied PNC at various points in the processing pipeline of both normal GRAPPA reconstructed EPI data and data with temporally updated GRAPPA weights (tGRAPPA).

2062.   The effects of coil compression on simultaneous multislice and conventional fMRI
Alan Chu1 and Douglas Noll1
1Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States

Multiple receive coils are needed for simultaneous multislice (SMS) imaging, resulting in large raw data storage requirements and long computation times for a typical SMS fMRI scan. In this abstract, we compare and evaluate the activation performance of varying levels of coil compression on both SMS and conventional fMRI scans. We use an efficient concentric ring trajectory that has the susceptibility signal recovery benefit of spiral-in imaging, and also facilitates the use of an SMS GRAPPA reconstruction. GRAPPA and SENSE SMS reconstruction results are compared with each other and with those of a conventional scan.

2063.   T2 prepared RUFIS: A new imaging paradigm for 3D whole-brain, silent and distortion-free BOLD fMRI
Ana Beatriz Solana Sánchez1, Anne Menini1, Laura Sacolick1, Nicolas Hehn1, and Florian Wiesinger1
1GE Global Research, Garching bei Muenchen, Bayern, Germany

This work presents a novel T2-prepared RUFIS method that tackles two eminent technical challenges of current BOLD fMRI: acoustic noise and geometric distortions. The method was tested and compared with GE-EPI and SE-EPI in healthy volunteers scanned at 3T using a two-segment T2 prepared RUFIS approach in motor and auditory tasks. Additionally, an improved approach using single-shot and further reduced acoustic noise was tested. The method showed a reduction of 40 dB(A) in LAeq acoustic noise measurement with respect to EPI-based methods, lack of geometrical distortions and consistent BOLD response, less sensitive (~1.3% BOLD change) but apparently spatially more specific.

2064.   Poisson-like property of spontaneous event trains and its relationship to scale-free dynamics
Jingyuan Chen1 and Gary Glover1
1Electrical Engineering, Stanford University, Stanford, CA, United States

In the present study, we demonstrated that (1) the scale-free dynamics of BOLD time series can be simulated by the convolution of spontaneous event trains and hemodynamic response functions; (2) the scale-free BOLD time series driven by the spontaneous event train may explain (at least partially) the scale-free property reported by previous fMRI literature; (3) Scale-free dynamics of fMRI time series may carry non-neural information, e.g. local hemodynamic fluctuations, suggesting caution in studies attempting to employ metrics such as Hurst exponent as biomarkers for neuroimaging investigations.

2065.   Improvement of task-based and resting-state fMRI using GRAPPA accelerated EPI with a FLASH based reference scan
Siyuan Liu1, Lalith Talagala2, Souheil Inati3, Yisheng Xu1, Ho Ming Chow1, Gang Chen4, and Allen Braun1
1NIDCD, National Institutes of Health, Bethesda, Maryland, United States, 2NMRF/NINDS, National Institutes of Health, Bethesda, MD, United States, 3FMRIF/NIMH, National Institutes of Health, Bethesda, MD, United States, 4SSCC/NIMH, National Institutes of Health, Bethesda, MD, United States

GRAPPA parallel acquisition technique (PAT) is frequently used in current fMRI EPI protocols to reduce EPI distortions and to increase the time resolution. Here, we demonstrated that when FLASH rather than EPI based reference scans were used in GRAPPA accelerated EPI, the sensitivity to detect brain activations increased in task-related fMRI and such an increase could be critical in detecting activated regions with small effect sizes at the group level. Using FLASH reference scans also improved the group-level resting-state functional connectivity results. All improvements are attributed to the enhancement of temporal SNR when using FLASH based reference scans.

2066.   Novel heterogeneity analysis of resting-state fluctuations in first-fit seizures and new-onset epilepsy
Lalit Gupta1, Mariëlle Vlooswijk2, Rob P. W. Rouhl2, Rick Janssens2, Anton de Louw3, Bert Aldenkamp3, Shrutin Ulman1, René M.H. Besseling4, Paul A.M. Hofman2, Jacobus F. A. Jansen4, and Walter H Backes4
1Philips India Ltd., Bangalore, Karnataka, India, 2Dept of Neurology, Maastricht University Medical Center, Maastricht, Netherlands, 3Epilepsy Center Kempenhaeghe, Heeze, Netherlands, 4Department of Radiology, Maastricht University Medical Center, Maastricht, Netherlands

Temporal heterogeneity in BOLD time-series in patients with a suspect of a single epileptic seizure (first-fit) has been compared to patients with new-onset epilepsy and healthy controls. Known temporal heterogeneity measures, including fractional amplitude of low frequency fluctuations and regional homogeneity, were used for time-series analysis. Results suggest that particularly for the low frequency range, 0.02-0.09 Hz, first-fit patients show decreased amplitude of the BOLD fluctuations. These effects show that the analysis of frequency fluctuations has potential to predict which patients are at increased risk to develop epilepsy after a single seizure.

2067.   
Vascular Autocalibration of fMRI (VasA fMRI) Improves Sensitivity of Population Studies
Samira M Kazan1, Siawoosh Mohammadi1, Martina F Callaghan1, Guillaume Flandin1, Robert Leech2, Aneurin Kennerley3, Christian Windischberger4, and Nikolaus Weiskopf1
1Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom, 2Cognitive, Clinical and Computational Neuroimaging Lab, University of London, Imperial College, London, United Kingdom, 3Department of Psychology, University of Sheffield, Sheffield, United Kingdom, 4MR Centre of Excellence, Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria

Functional MRI group studies play a central role in basic and clinical neuroscience, but without large group sizes their statistical powers are rather low, mainly due to high inter-subject variance. We present a novel auto-calibration method, termed VasA fMRI, which significantly reduces variation and increases statistical power by accounting for vascularization differences between subjects. Sensitivity increases exceeded 20% in different brain areas, which is comparable to the gain achieved by a 40% increase in group size or by going from 1.5T to 3T. VasA fMRI does not require additional reference scans and can be applied to any task-related fMRI dataset. It facilitates investigation of subtle effects, the use of smaller groups and revisiting previous studies that were statistically underpowered.

2068.   Improved Retrospective Motion Correction in fMRI using A Biophysical Model
Tim M Tierney1, Louise J Croft2, Maria Centeno1, Elhum A Shamshiri1, Suejen Perani1,3, Torsten Baldeweg2, Christopher A Clark1, and David W Carmichael1
1Developmental Imaging and Biophysics, UCL Institute of Child Health, London, United Kingdom, 2Cognitive Neuroscience and Neuropsychiatry, UCL Institute of Child Health, London, United Kingdom, 3Department of Basic and Clinical Neuroscienc, KCL Institute of Psychiatry, Psychology & Neuroscience, London, United Kingdom

Subject head motion negatively affects task based fMRI and connectivity based studies. We have developed a biophysical model named FIACH to address these issues. FIACH is a biophysical model of motion correction that employs a two-step procedure for motion correction. We have demonstrated it performs better than four other methods of retrospective motion correction. This was demonstrated in a paediatric population during overt speech where subject motion is common. FIACH is also capable of correcting data near inferior temporal areas. These areas have proven problematic for fMRI and FIACH provides the opportunity to improve knowledge of these areas function.

2069.   Analysis of Sampling Rate (TR) Dependence of Hurst Exponent of FMRI BOLD Time Series
Muhammad Kaleem1 and Dietmar Cordes2
1Ryerson University, Toronto, Ontario, Canada, 2Lou Ruvo Center for Brain Health, Las Vegas, Nevada, United States

The abstracts presents a study of the Hurst exponent of fMRI BOLD time-series acquired at different sampling rates (TR). The Hurst exponent is related to the spectral characteristics of a time-series, and the change in the Hurst exponent value at different TRs due to frequency aliasing is demonstrated.

2070.   Signal Processing Spreads a Voxel’s Temporal Frequency Task-Activated Peak and Induces Spatial Correlations in Dual-Task Complex-Valued fMRI
Mary C. Kociuba1 and Daniel B. Rowe1,2
1Department of Mathematics, Statistics, and Computer Science, Marquette University, Milwaukee, Wisconsin, United States, 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States

Given a dual-task experimental design with different task periods, two distinct task-activated peaks are expected. Signal processing will alter the activated voxel’s temporal frequency spectrum, by spreading voxel task activated peaks temporally and spatially into neighboring frequencies and voxels. If the period of both tasks falls within a close range, without knowledge of the expected task-activated regions, it is difficult to resolve the task to the associated region after processing. Modeling the impact of signal processing, with respect to the task-activated frequency, is critical to developing methods to account for artificial correlations, while preserving the signal of interest.

2071.   Laminar time course extraction over extended cortical areas
Tim van Mourik1, Jan PJM van der Eerden1, and David G Norris1
1Donders Centre for Cognitive Neuroimaging, Radboud University Nijmegen, Nijmegen, Netherlands

We propose a new method to reliably and accurately extract laminar time courses from fMRI data. We use a spatial General Linear Model to disentangle laminar signals instead of interpolating through and integrating over a cortical area. We show that the Point Spread Function of the method is much sharper, proving better signal extraction. This may allow for larger voxel sizes to get around problems such as low SNR and severe distortions in EPI with which laminar analysis has dealt.

2072.   bOVOC: 200 Hz balanced One-Voxel-One-Coil MREG at 9.4T
Klaus Scheffler1, Gabriele Lohmann1, Christian Mirkes1, Shajan Gunamony1, and Philipp Ehses1
1MRC department, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, Tübingen, Germany

Balanced OVOC is a variant of the FLASH-based One-Voxel-One-Coil (OVOC) method introduced by Jürgen in 2006. It aims to measure functional responses at a very high temporal resolution as no or just one spatial encoding direction is applied. Measurements of functional responses to visual checkerboard stimulation at a temporal resolution of 5 ms and one-dimensional resolution of 1 mm using a small surface coil of 3 cm are presented. With an echo time of 2.5 ms for bOVOC signal changes are mostly related to T2 and diffusion changes.

2073.   
Distortion-Corrected High Resolution Zoomed fMRI at 9.4 T
Jonas Bause1,2, Myung-Ho In3, Philipp Ehses1,4, G. Shajan1, Oliver Speck3, Rolf Pohmann1, and Klaus Scheffler1,4
1High-Field Magnetic Resonance Center, Max Planck Insitute for Biological Cybernetics, Tuebingen, Germany, 2Graduate Training Centre for Neuroscience, University of Tuebingen, Tuebingen, Germany, 3Department for Biomedical Magnetic Resonance, University of Magdeburg, Magdeburg, Germany, 4Department of Biomedical Magnetic Resonance, University of Tuebingen, Tuebingen, Germany

High-resolution EPI at ultra-high field often suffers from distortions and requires a short time to k-space center in order to achieve the optimal BOLD contrast. In this work, zoomed functional imaging was combined with the point spread function mapping technique in order to obtain images with re-duced distortions acquired with the optimal TE for fMRI at 9.4T. The approach was tested in a functional experiment with 0.8 mm and 0.65 mm iso-tropic resolution. Activation maps obtained from the distortion corrected images showed a higher number of activated voxels then the maps from the undistorted images and match well with anatomy.

2074.   
Factors influencing learning to self-regulate brain activity using real-time fMRI: comparison between conscious strategy and contingent feedback
Pradyumna Sepúlveda1,2, Ranganatha Sitaram3,4, Mohit Rana3,5, Tomás Ossandón6, Marcelo Andía1,7, Cristián Montalba1, Sergio Uribe1,7, Pablo Irarrázaval1,2, Sergio Ruiz4,6, and Cristián Tejos1,2
1Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, 2Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, 3Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States, 4Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany, 5Graduate School of Neural & Behavioural Sciences, International Max Planck Research School, University of Tübingen, Tübingen, Germany,6Department of Psychiatry, Faculty of Medicine, Interdisciplinary Center for Neuroscience, Pontificia Universidad Católica de Chile, Santiago, Chile, 7Radiology Department, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile

Healthy subjects and patients can self-regulate brain activity locally or globally using real time fMRI neurofeedback (rtfMRI NF), often accompanied by observable behavioral changes. Furthermore, new therapeutic and research applications have encouraged a growing number of studies using rtfMRI NF. Despite the interest, the relevance of different factors in the self-regulation learning process is yet to be known. In this study we compared the influence of using a conscious mental strategy during neurofeedback versus pure contingent feedback. Results indicate that the use of a conscious strategy does not necessarily improve learning with respect to only NF.

2075.   Functional connectivity in Task Switching Paradigm
Mitsunobu Kunimi1, Sachiko Kiyama1, and Toshiharu Nakai1
1National Center for Geriatrics and Gerontology, Obu, Aichi, Japan

This study attempted to demonstrate the extent of the task load-dependent augmentation of brain activation and the change of functional connectivity during the TSP. Twenty healthy young adults (mean age: 22.80 }3.44, 9 males) participated in the study. The significant activation was observed in the frontal and parietal region and it was augmented as task load increased. In addition, the functional connectivity was extended depending on task load. These results were considered that the network of these regions works as a central executive, and it controls switch of attention, task-set reconfiguration and inhibition during TSP.

2076.   High-resolution functional imaging in the human brain using passband bSSFP at 9.4T
Klaus Scheffler1,2 and Philipp Ehses1,2
1Dept. of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany, 2High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany

Passband bSSFP at 9.4T provides highly reproducible and stable functional activation maps. Results were compared to GE-EPI and SE-EPI. Based on the very short TE of 2.1 ms for bSSFP, T2*-related signal changes are expected to be very small, which is supported by the similarity of bSSFP and SE-EPI activation maps. As bSSFP is distortion-free, direct overlay to anatomical images is possible. Furthermore, the spatial resolution is not smoothed along the PE-direction due to T2*-related blurring as in EPI-based methods.

2077.   Automated and Individualized fMRI Processing for Pre-surgical Mapping: Comparison with MEG and Cortical Stimulation.
Tynan Stevens1, Tim Bardouille2,3, Gerhard Stroink1, David Clarke1,4, Ryan D'Arcy5, and Steven Beyea1,2
1Dalhousie University, Halifax, Nova Scotia, Canada, 2BIOTIC, Halifax, Nova Scotia, Canada, 3IWK Hospital, Halifax, Nova Scotia, Canada, 4QEII Health Sciences Centre, Halifax, Nova Scotia, Canada, 5Simon Fraser University, Burnaby, British Columbia, Canada

Functional MRI for pre-surgical mapping is hampered by a high degree of individual variability, requiring experts to make appropriate data processing choices. We have developed a method for automatic and individualized processing of pre-surgical mapping using the ROC-r framework. This method optimizes both pre-processing pipelines and activation thresholds on a case-by-case basis. We compare localization obtained for fMRI with more direct measures of neural activity (MEG, cortical stimulation, and sensory evoked potentials). We find highly concordant spatial localization between modalities, showing the potential of automated optimization of fMRI processing for pre-surgical mapping.

Wednesday 3 June 2015
Exhibition Hall 10:00 - 12:00

2078.   Disrupted Resting State Brain Connectivity in Fetal Complex Congenital Heart Disease
Vincent Kyu Lee1,2, Mark DeBrunner3, Jennifer A. Johnson3, Jodie Votava-Smith4, Vidya Rajagopalan5, Rafael Ceschin1,2, Michelle Gruss2, Frederick S. Sherman3, and Ashok Panigrahy1,2
1Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Radiology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States, 3Cardiology, Children's Hospital of Pittsburgh, Pennsylvania, United States, 4Cardiology, Children's Hospital of Los Angeles, California, United States, 5Children's Hospital of Los Angeles, Pennsylvania, United States

This is an initial presentation of 3T parallel transmission study on fetal complex congenital heart disease (CHD). ICA analysis was used with resting BOLD of fetal CHD patients to test evidence of disruption in fetal resting state networks (RSN) compared to healthy controls, and whether the degree of disruption of fetal RSN within the complex CHD group is related to the degree of presumed fetal cerebral oxygenation saturation. Our preliminary results provide evidence of disruption of the development of normal RSN in the frontal and posterior regions of the brain in complex CHD fetal cases compared to healthy fetal controls.

2079.   Investigation of optimal echo time for resting-state fMRI acquisition in Newborn infants
Maryam Abaei1, Eugene P Duff2, Tomoki Arichi1,3, Jonathan O'Muircheartaigh1,4, Emer Hughes1, Giulio Ferrazzi1, Steve M Smith2, Serena Counsell1, A David Edwards1,5, Daniel Rueckert6, and Joseph V Hajnal1,5
1Centre for the Developing Brain, King's College London, London, London, United Kingdom, 2Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom,3Department of Bioengineering, Imperial College, London, United Kingdom, 4Institute of Psychiatry, King's College London, London, United Kingdom, 5Division of Imaging Sciences and Biomedical, King's College London, London, United Kingdom, 6Biomedical Image Analysis Group, Department of Computing, Imperial College, London, United Kingdom

blood oxygen level dependen contrast-to-noise ratio is known to be maximal when the acquisition sequence echo time is matched to the T2* of the tissue of interest.We aimed to identify the optimal echo-time for performing resting-state fMRI studies in a test subject group.

2080.   Resting state functional connectivity predicts changes in interoceptive awareness following mindfulness training
Maryam Falahpour1, Lori Haase2, Martin P. Paulus2, and Thomas T. Liu1
1Center for Functional MRI, University of California San Diego, La Jolla, CA, United States, 2Department of Psychiatry, University of California San Diego, La Jolla, CA, United States

Mindfulness is a complex construct consisting of regulated attention, knowledge that events are momentary, and absence of emotion or cognitive appraisal of events. The primary aim of the present study was to investigate the relation between the functional connectivity and the changes in self-assessment scores after training in elite athletes. We found that measures of functional connectivity obtained before training can predict changes in subjects’ self-assessment of interoceptive awareness.

2081.   The Relationship between Level of Consciousness and Variability of Brain Connectivity
Christina Hamilton1, Yuncong Ma1, and Pablo Perez1
1Pennsylvania State University, State College, PA, United States

Anesthesia is an altered state of consciousness that can be characterized by a complex interaction between an individual’s level of arousal and awareness. Resting-state functional magnetic resonance imaging (rsfMRI) has been shown to be a useful tool for investigating systems-level changes in functional brain connectivity during anesthesia-induced unconsciousness (AIU). Here we use rsfMRI and behavioral measures of anesthetic depth to investigate the dose-dependent effect of isoflurane on functional brain connectivity. These findings provide insight into the relationship between neuroimaging data and behavioral measures of anesthetic depth, which may provide us with a better understanding of the neural basis of AIU.

2082.   Modulation of functional connectivity during finger tapping and resting state in patients with MS
Xiaopeng Zhou1, Katherine A Koenig1, Erik B Beall1, Lael Stone1, Robert Bermel1, Michael D Phillips1, and Mark J Lowe1
1The Cleveland Clinic, Cleveland, Ohio, United States

We investigated the modulation of motor connectivity in patients with multiple sclerosis (MS) and controls by acquiring fc in 3 conditions (rest, 2 Hz paced finger tapping and self-paced complex finger tapping).Significant fc changes in some brain regions during 2 motor tasks from rs were exhibited, showing fc network can be modulated under different states in controls and patients with MS. There was decreased fc in certain regions of patient compared with controls. The observation that more group differences were observed in the resting state suggests that this may be the most effective way of studying functional impairment in MS.

2083.   Reduced brain functional network dynamics in propofol sedation characterized by modularity and time delayed network mutual information analysis
Guangyu Chen1, Xiaolin Liu1, Anthony G Hudetz2, and Shi-Jiang Li1
1Biophysics, Medical College of Wisconsin, milwaukee, WI - Wisconsin, United States, 2Department of Anesthesiology, Medical College of Wisconsin, milwaukee, WI - Wisconsin, United States

Time delayed network mutual information index (TD-NMI) was used to measure the dynamics of functional network modules in wakeful baseline, deep sedation with propofol, and recovery. Compared with wakeful baseline, all identified brain modules showed significantly reduced dynamics in deep sedation. During recovery, the frontal-posterior control module showed fully recovered dynamics, visual module showed partial recovery, while the default mode network and motor-sensory modules showed no sign of recovery. This study shed light, from a network dynamics perspective, on the relative importance of brain network modules and their association with the different states of propofol sedation.

2084.   Increased variability across time accounts for reduced connectivity within the default mode network in autism: a dynamic fcMRI study
Maryam Falahpour1, Wesley K. Thompson2, Angela E. Abbott3, Mark E. Mulvey3, Michael Datko3, Ralph-Axel Müller3, and Thomas T. Liu1
1Center for Functional MRI, University of California San Diego, La Jolla, CA, United States, 2Department of Psychiatry, University of California San Diego, La Jolla, CA, United States,3Brain Development Imaging Lab, Department of Psychology, San Diego State University, CA, United States

fMRI resting state studies of subjects with autism spectrum disorder (ASD) have revealed altered functional connectivity (FC) in the default mode network (DMN), as compared to typically developed subjects. We hypothesized that the group differences in FC might reflect differences in the temporal variability of the FC measures. We used mediation analysis to examine the relation between FC and the temporal variability in FC between the two major nodes of the DMN, the posterior cingulate cortex and the medial prefrontal cortex. Our results suggest that under-connectivity in ASD population may be in part due to higher temporal variability in FC.

2085.   Validation of in vivo structural template of human brainstem nuclei by fMRI at 7 Tesla
Marta Bianciardi1, Nicola Toschi1,2, Cornelius Eichner1, Kawin Setsompop1, Jonathan R. Polimeni1, Bruce R. Rosen1, and Lawrence L. Wald1
1Department of Radiology, A.A. Martinos Center for Biomedical Imaging, MGH and Harvard Medical School, Boston, MA, United States, 2Medical Physics Section, Department of Biomedicine and Prevention, Faculty of Medicine, University of Rome “Tor Vergata”, Rome, Italy

The aim of this work was to validate our recently developed in-vivo structural template of human brainstem-nuclei (Bn) of the ascending-arousal, autonomic and motor systems by 1.1mm-isotropic fMRI at 7Tesla. For each of the 18 Bn-labels of the structural template, a spatially matched functional parcel in the brainstem was identified by ICA. Our results also showed that structural Bn-labels were functionally connected to specific brain regions as expected from previous work. This work provides a preliminary validation of the in-vivo structural Bn template, which is a key step towards its use in future studies of human brainstem function and pathology.

2086.   Functional Connectivity Analysis: Performance Comparison of Gradient and Spin Echo EPI Simultaneously Acquired
Brice Fernandez1, Victor Spoormaker2, Philipp Sämann2, and Michael Czisch2
1Applications & Workflow, GE Healthcare, Munich, Germany, 2Neuroimaging Unit, Max Planck Institute of Psychiatry, Munich, Germany

Resting state functional connectivity is an attractive tool to study affective and mood disorders. Gradient-echo EPI (GRE-EPI) is affected by strong signal drops in brain regions critical for emotional processing. Spin-echo EPI (SE-EPI) is known to not suffer from this problem. Here, we use a Hybrid EPI pulse sequence to simultaneously acquire both the GRE-EPI and the SE-EPI. The comparison of both acquisition methods shows that meaningful signal fluctuations can be recovered in susceptibility affected brain regions using SE-EPI, while minor differences in functional connectivity were observed for unaffected brain areas. Furthermore, GRE-EPI is more prone to global signal artefacts.

2087.   Slice-Dynamic Shimming for Simultaneous Brain and Spinal Cord fMRI
Christine Law1, Haisam Islam1, Gary Glover1, and Sean Mackey1
1Stanford University, Stanford, CA, United States

Simultaneous brain/spine fMRI has not been adopted due to the challenge of shimming multiple regions of high magnetic field inhomogeneity. A dynamic shim update technique was recently proposed to address this issue that used a separate set of the linear gradients and a frequency offset for the brain and spinal cord. We propose a technique to advance this concept by applying optimal linear shim values on a per-slice basis. Our slice-based technique, which calculates optimal shimming from a field map, would not be possible using the shim procedure provided by a scanner manufacturer.

2088.   T2*-Weighted Inner-Field-of-View Echo-Planar Imaging of the Spinal Cord
Jürgen Finsterbusch1,2
1Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2Neuroimage Nord, University Medical Centers Hamburg-Kiel-Lübeck, Hamburg-Kiel-Lübeck, Germany

The feasibility of inner-field-of-view EPI based on 2D-selective RF excitations to acquire T2*-weighted images of the human spinal cord in vivo is demonstrated. Compared to conventional, slice-selective EPI, the readout echo train is shortened reducing geometric distortions and lower sections of the spinal cord can be covered without the need for excessive FOVs to avoid aliasing artifacts. Like for conventional EPI, slice-specific z-shimming can be applied to minimize signal dropouts related to through-slice dephasing. Thus, BOLD-based functional imaging may become feasible throughout the spinal cord.

2089.   The interaction of physiological noise correction with multi and single echo ICA denoising
Jennifer Evans1, Prantik Kundu2, and Peter Bandettini1
1NIH, Bethesda, Maryland, United States, 2Mount Sinai, New York, United States

Physiological noise removal is an important part of the fMRI preprocessing pipeline but the collection of good physiological data adds an extra complication to data acquisition. Here we look at ICA denoising techniques that are currently available that attempt to remove “non-signal” components either by prior identification (FIX) or based on the amount of BOLD scaling (MEICA) using multi-echo acquisition and the effect of the use of physiological noise regressors on the denoised data.

2090.   Neural activity associated with spontaneous eye opening and closure in the awake macaque
Catie Chang1, David A Leopold2, Hendrik Mandelkow1, Marieke L Schölvinck3, and Jeff H Duyn1
1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, NINDS, NIH, Bethesda, MD, United States, 2Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, NIMH, NIH, Bethesda, MD, United States, 3Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main, Germany

Here, we investigated the spatial and temporal relationship between neural activity and a behavioral index of vigilance state (spontaneous eye open/closure in darkness) using simultaneous fMRI and electrophysiological data from unanesthetized macaques in the resting state. We observed a robust relationship between resting-state electrophysiological and fMRI signals and our measure of eye open/closure, with eye opening correlated with decreases in fMRI signal across most of the cortex, and with increases in the thalamus and cerebellum. Temporal analysis indicated that thalamic and cerebellar regions exhibited increases in signal that preceded the signal decreases in cortex.

2091.   Propofol-Induced Reduction of Functional Connectivity in Large-Scale Brain Networks Defined at Fine Spatial Scales
Xiaolin Liu1, Kathryn K. Lauer2, B. Douglas Ward1, Jeffrey R. Binder3, Shi-Jiang Li1, and Anthony G. Hudetz2
1Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States, 2Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States, 3Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States

We proposed a neuroimaging-based anatomical-functional parcellation algorithm for defining brain networks at arbitrary spatial scales and extended this approach to determine global changes in brain functional connectivity during propofol sedation at two sedation levels as compared to wakeful baseline and recovery. Propofol sedation and its deepening are associated with a global reduction of brain functional connectivity. Reduced node connectivity in deep sedation showed different degrees of involvement of cortical and subcortical systems. The study represents a way of comprehensively characterizing complex functional and behavioral changes in sensory, attentional, cognitive and motor systems of the brain during anesthetic sedation.

2092.   Trends, seasonality, and persistence of resting-state fMRI over 185 weeks
Ann Sunah Choe1,2, Craig K Jones3,4, Suresh E Joel3,4, John Muschelli5, Visar Belegu6,7, Martin A Lindquist5, Brian S Caffo5, Peter CM van Zijl3,4, and James J Pekar3,4
1Radiology and radiological sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Radiology and radiological sciences, Johns Hopkins School of Medicine, MD, United States, 4F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, MD, United States, 5Biostatistics, Bloomberg School of Public Health, Johns Hopkins University, MD, United States, 6Neurology, Johns Hopkins School of Medicine, MD, United States, 7International Center for Spinal Cord Injury, Kennedy Krieger Institute, MD, United States

Despite strong interest in using resting state fMRI (rsfMRI) outcome measures as imaging biomarkers for clinical studies, the temporal structure (e.g., seasonality) of such measures is poorly understood. This study aimed to assess the existence of temporal structure in three commonly used rsfMRI outcomes measures; namely spatial map similarity, temporal fluctuation magnitude, and between-network connectivity. A unique longitudinal dataset reporting on one healthy adult subject scanned on a weekly basis over 185 weeks enabled timeseries analysis on the measures of interest. Results revealed significant linear trend, annual periodicity, and persistence in many resting state networks, for all outcome measures.

2093.   Magnetic vestibular stimulation (MVS) influences fMRI resting-state fluctuations: The modulation of the default-mode network as an exemplary case
Rainer Boegle1,2, Thomas Stephan1,3, Matthias Ertl2,3, Stefan Glasauer1,4, and Marianne Dieterich1,3
1German Center for Vertigo and Balance Disorders, DSGZ IFB-LMU, Munich, Bavaria, Germany, 2Graduate School of Systemic Neurosciences, LMU, Munich, Bavaria, Germany,3Department of Neurology, LMU, Munich, Bavaria, Germany, 4Center for Sensorimotor Research, LMU, Munich, Bavaria, Germany

Recently it was demonstrated that healthy subjects inside MR machines develop a persistent nystagmus in darkness, while patients who are lacking bilateral peripheral vestibular function do not. We studied the influence of this magnetic vestibular stimulation (MVS) on fMRI resting-state fluctuations in healthy subjects, at 1.5Tesla and at 3Tesla. We found that significant modulation of the default mode network occurs, mainly in areas associated with vestibular function. As proposed for MVS, the modulation-scaling is significantly higher than the expected BOLD signal increase due to B0 without an additional modulation effect. We conclude that MVS does significantly modulate fMRI resting-state networks.

2094.   Inter-hemispheric connectivity (functional homotopy) is reduced in pediatric epileptic patients with corpus callosotomy
Peter S LaViolette1, Sean Lew2, Scott D Rand1, Manoj Raghavan3, Kurt Hecox3, and Mohit Maheshwari1
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, 2Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States, 3Neurology, Medical College of Wisconsin, Milwaukee, WI, United States

Interhemispheric functional connectivity can be modeled with a new technique called functional homotopy. We acquired resting-state fMRI (rs-fMRI) in two pediatric patients following corpus callosotomy (severing the corpus callosum) for treatment of refractory epilepsy. We calculated homotopy and compared their data to a control dataset to determine differences. We find global changes in interhemispheris connectivity due to the severing of the corpus callosum.

2095.   Functional Relevance of Spatial ICA and K-means Clustering
Jun Young Jeong1, Julia Druzbicki2, Kun-Han Lu1, Haiguang Wen1, and Zhongming Liu1,3
1Electrical and computer engineering, Purdue University, West Lafayette, IN, United States, 2Department of statistics, Purdue University, IN, United States, 3Weldon school of biomedical engineering, Purdue University, IN, United States

To facilitate the functional interpretation of the spatial patterns of resting state fMRI extracted by using either the K-means spatial clustering or spatial ICA, we compared them with the patterns obtained by applying these two methods to a large set of task activation maps. We confirmed the close correspondence between the resting state and task activation patterns extracted by using spatial ICA. However, we failed to establish a similar level of correspondence for the spatial k-means clustering. This distinction is speculated to have a methodological basis.

2096.   Analysis of High Frequency Resting State Networks in the Human Brain
Cameron William Trapp1, Kishore Vakamundi2, and Stefan Posse3
1Physics, UNM, Coralles, NM, United States, 2DEPARTMENT OF PHYSICS AND ASTRONOMY, UNIVERSITY OF NEW MEXICO, ALBUQUERQUE, NEW MEXICO, United States,3DEPARTMENT OF NEUROLOGY, UNIVERSITY OF NEW MEXICO, NM, United States

Mapping of intrinsic high frequency (> 0.5 Hz) resting state connectivity has been demonstrated in recent studies in motor and visual cortex. In this study we use multi-slab echo volumar imaging with 136 ms temporal resolution to compare resting state connectivity in 6 major resting state networks at frequencies below 0.3 Hz and at frequencies between 0.5 and 3.6 Hz. The high frequency connectivity in the brain corresponds strongly to connectivity observed within the low frequency RSNs. This preliminary study establishes resting state connectivity at frequencies > 0.5 Hz in multiple major RSNs.

2097.   Identification of state transitions and durations in resting-state functional connectivity
Sadia Shakil1, Chin-Hui Lee1, and Shella Keilholz1,2
1Georgia Institute of Technology, Atlanta, Georgia, United States, 2Emory University, Atlanta, Georgia, United States

Window size and offset in sliding window correlation may have an effect on correct identification of functional connectivity states. This effect was examined on controlled simulated networks formed with data taken from resting-state functional MRI scans.

2098.   Subcortical structures in resting state fMRI: uncovering functional networks involving deep-brain structures using non-local mean denoising at 1.5Tprime or minute
Michaël Bernier1, Maxime Chamberland1, Stephen Cunnane2, and Kevin Whittingstall3
1Nuclear medecine and radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada, 2Institut universitaire de gériatrie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada, 3Diagnostic radiology, Université de Sherbrooke, Sherbrooke, QC, Canada

Using non-local mean denoising, we present a reliable method to efficiently uncover subcortical correlated areas in task-based functional network. The regions of interest (ROIs) obtained in both subcortical areas and key structures involving task-based activations with our denoising pipeline allow a better representation of known functional networks involving subcortical structures in resting state fMRI in typical clinical MRI (1.5 T).

2099.   Spin-locked Oscillatory Excitation (SLOE): Towards in-vivo Detection of Oscillating Neuronal Currents
Jingwei Sheng1, Yuhui Chai1, Bing Wu2, Weinan Tang1, and Jia-Hong Gao1
1Center for MRI Research, Peking University, Beijing, Beijing, China, 2GE Healthcare MR Research China, Beijing, China

We demonstrated the superiority of the spin-locked oscillatory excitation (SLOE) method proposed by our group in detecting sub-nanotelsa oscillatory fields in a phantom study. Furthermore, this sensitivity was verified in anesthetic rats with similar applied oscillatory fields. Our proposed SLOE method showed extremely high detection sensitivity that enables 3T MR scanners for the first time to direct detect applied sub-nT oscillatory magnetic fields both in phantom and rats. The milestone achieved in this work paves the way towards direct mapping neuronal currents by MRI in the study of human brain function.

2100.   SEEP contrast highlights different functional connectivity networks compared to BOLD resting state fMRI
Venkatagiri Krishnamurthy1, Romeo S. Cabanban2, and Kaundinya S. Gopinath1
1Dept. of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States, 2Center for Systems Imaging, Emory University, Atlanta, GA, United States

Blood oxygen level dependent (BOLD) resting state fMRI (rsFMRI) has been the most widely employed method to explore resting-state functional connectivity (rsFC) in brain networks. Signal enhancement by extravascular protons (SEEP) has been advanced as an alternate mechanism to assess brain activation. In this study we compared rsFC networks highlighted by BOLD- and SEEP-contrast rsFMRI. The results of this study show that rsFMRI obtained with SEEP contrast exhibits differential sensitivity to functional connectivity networks compared to BOLD rsFMRI. While BOLD rsFC networks exhibit higher sensitivity to state-dependent brain networks (e.g. DMN), the SEEP contrast exhibits higher sensitivity to anatomic connections.

2101.   Automated Subject-Specific Seed Optimization Improves Dectection of Resting-state fMRI connectivity
KISHORE VAKAMUDI1,2, ELENA ACKLEY2, and STEFAN POSSE1,2
1DEPARTMENT OF PHYSICS AND ASTRONOMY, UNIVERSITY OF NEW MEXICO, ALBUQUERQUE, NEW MEXICO, United States, 2DEPARTMENT OF NEUROLOGY, UNIVERSITY OF NEW MEXICO, ALBUQUERQUE, NEW MEXICO, United States

Seed-based connectivity analysis (SCA) is widely used to study functional connectivity. However, it suffers from variability inherent in investigator-specific and subject-specific seed selection dependencies. The current Automated Subject-Specific Seed Optimization (ASSSO) method uses an iterative brain atlas based approach identifies the optimal seed locations to maximize the detected RSN connectivity in individual subjects. This seed-selection will maximize the sensitivity for detecting RSN dynamics at short and long time scales across the entire brain in real-time. This methodology is expected to have important applications in presurgical mapping.

2102.   Resting State Network Detection with Searchlight on Functional MRI
Shiyang Chen1,2, Hasan Ertan Cetingul2, Xiaoping Hu1,3, and Mariappan S. Nadar2
1The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States, 2Imaging and Computer Vision, Siemens Corporation, Corporate Technology, Princeton, NJ, United States, 3Biomedical Imaging Technology Center, Emory University, Atlanta, GA, United States

Resting state networks (RSNs) are important biomarkers for disease diagnosis, (e.g. Alzheimer’s disease). The conventional methods to detect RSNs require a spatial smoothing step to compensate the low SNR of fMRI, and they assume the brain connectivity is voxel-to-voxel. These steps and assumptions are still controversial. We propose a searchlight plus multivariate regression method to detect the RSNs, which is able to detect region-to-region brain connection and can be performed on unsmoothed or slightly smoothed fMRI data. We validate this method by detecting the conventional RSNs, and we also found additional brain regions that are connected in the RSNs.

2103.   Mapping effective connectivity in the mouse brain using Granger causality
Md Taufiq Nasseef1,2, Adam Liska1,2, Stefano Panzeri1, and Alessandro Gozzi1
1Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, TN, Italy, 2Center for Mind/Brain Sciences, University of Trento, Rovereto, TN, Italy

We have recently shown that the mouse brain contains distributed resting-state fMRI (rsfMRI) networks including a putative “default-mode” like network (DMN). To map the direction of information flow within this network, we have used Granger Causality (GC), a directed measure of functional connectivity, to describe the dominant direction of causation among four key nodes of the mouse DMN. We provide evidence of directional information transfer between nodes of this network that replicate patterns recently described for the human DMN, thus corroborating the presence of an evolutionary conserved DMN precursor in the rodent brain.

2104.   Retrospective nonlinear spin history motion artifact modeling and correction with SLOMOCO
Erik Beall1 and Mark Lowe1
1Imaging Institute, Cleveland Clinic, Cleveland, OH, United States

Head motion in BOLD functional imaging is a serious problem. Current methods all assume the artifact is linearly related to head motion. We show this assumption is incorrect and demonstrate a fully retrospective spin history modeling and correction tool.

2105.   SLOMOCO-derived slicewise head motion produces physiologic signals and reveals that motion is hard to characterize
Erik Beall1 and Mark Lowe1
1Imaging Institute, Cleveland Clinic, Cleveland, OH, United States

Head motion is a major confound in BOLD imaging. Until very recently, it was only possible to use volumetric motion parameters. Hence, the distribution of typical head motion and the frequency spectrum at the slice level are unknown. We investigate these and find that while these are different, its not unexpected given the different frequency with which each measure is operating. However, we also find clear physiologic noise signatures and demonstrate that SLOMOCO can be used to obtain pulse and respiration traces.

Wednesday 3 June 2015
Exhibition Hall 10:00 - 12:00

2106.   Modification of a Standard MR-compatible EEG Cap for Improved EEG Neurofeedback with Simultaneous fMRI
Vadim Zotev1, Ahmad Mayeli1,2, and Jerzy Bodurka1,3
1Laureate Institute for Brain Research, Tulsa, OK, United States, 2Electrical and Computer Engineering, University of Oklahoma, Tulsa, OK, United States, 3College of Engineering, University of Oklahoma, Tulsa, OK, United States

Implementation of EEG neurofeedback (EEG-nf) with simultaneous fMRI requires an accurate removal of EEG-fMRI artifacts in real time. We describe a simple and safe modification of a standard MR-compatible EEG cap that substantially improves signal quality for EEG-nf based on frontal EEG asymmetry. The modified cap includes two reference contours for two frontal EEG channels used to provide EEG-asymmetry-nf. Subtraction of fitted reference signals provides random-motion and cardioballistic artifact power suppression by 6...8 dB. The proposed EEG signal correction should be performed in real time after the MR artifact removal and prior to the average cardioballistic artifact subtraction.

2107.   Contribution of A Brain-state Specific Neurophysiological Event to Large-scale fMRI Signal Fluctuations
Xiao Liu1, Toru Yanagawa2, David A Leopold3, Marieke Schölvinck4, Catie Chang1, Hiroaki Ishida5, Naotaka Fujji2, and Jeff H. Duyn1
1AMRI, LFMI, NINDS, NIH, Bethesda, MD, United States, 2BSI, RIKEN, Saitama, Japan, 3Laboratory of Neuropsychology, NIMH, NIH, Bethesda, MD, United States, 4Ernst Strüngmann Institute for Neuroscience, Frankfurt, Hessen, Germany, 5Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

To investigate the neural correlate of large-scale signal fluctuation in resting state fMRI (rsfMRI) and understand its relationship to brain state, we examined the ECoG power recorded from large electrode grids in macaques during eyes-open, eyes-closed wakefulness, and sleep conditions. We observed a brain-state-sensitive, stereotypical event whose spatiotemporal characteristics resembled the rsfMRI characteristics. With an independent dataset of concurrent fMRI-electrophysiology, we further confirmed that the identified events were directly associated with global changes in resting-state fMRI signal.

2108.   EEG-fMRI integration for the study of physiological response to Intermittent Photic Stimulation
Eleonora Maggioni1,2, Claudio Zucca1, Gianluigi Reni1, Fabio Maria Triulzi3, Anna Maria Bianchi2, and Filippo Arrigoni1
1Scientific Institute IRCCS E.Medea, Bosisio Parini, LC, Italy, 2Department of Electronics Information and Bioengineering, Politecnico di Milano, Milano, MI, Italy, 3Neuroradiology Unit, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, Milano, MI, Italy

This contribution is focused on the analysis of physiological response to intermittent photic stimulation using simultaneous EEG-fMRI data. The EEG-fMRI integration allowed to investigate the phenomena of neurovascular coupling, in particular it gave insight into the neural mechanisms underlying negative BOLD responses to visual stimulations.

2109.   Metabolic basis for the "rest" condition in fMRI: Comparison of eyes open vs. closed states reveals constancy of glucose metabolism across networks
Garth John Thompson1, Valentin Riedl2,3, Timo Grimmer3,4, Alexander Drzezga5, Peter Herman1, and Fahmeed Hyder1,6
1Diagnostic Radiology, Magnetic Resonance Research Center, Yale University, New Haven, CT, United States, 2Neuroradiology, Nuclear Medicine, Universität München, München, Germany, 3Technische, Universität München - Neuroimaging Center, München, Germany, 4Psychiatry, Universität München, München, Germany, 5Nuclear Medicine, Uniklinikum, Koeln, Germany, 6Biomedical Engineering, Yale University, New Haven, CT, United States

While resting-state fMRI (R-fMRI) is powerful, specific "rest" condition parameters (e.g., eyes closed vs. open) vary study to study. Subjects underwent simultaneous R-fMRI and PET scans with eyes open and closed. R-fMRI data were used to generate networks, whereas PET data mapped glucose consumption (CMRglc). While globally higher CMRglc was observed with eyes open, there were insignificant CMRglc differences across networks for either state. Since all R-fMRI networks were detected regardless of the state, CMRglcconstancy across networks for a state suggests that the brain easily transitions between these networks and either "rest" condition can be used for R-fMRI.

2110.   Simultaneous acquisition of structural and resting state functional connectivity data using a volumetric navigated diffusion sequence
Mwape Mofya1, Alkatafi Ali Alhamud1, Paul A. Taylor1,2, André J. W. van der Kouwe3, and Ernesta M. Meintjes1
1MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Cape Town, South Africa, 2African Institute for Mathematical Sciences (AIMS), South Africa, 3Massachusetts General Hospital, Boston, Massachusetts, United States

Simultaneous DTI-fMRI data collection has previously been unsuccessful, due to mutual interference of the acquired DTI and fMRI signals. In this work, a single 3D EPI navigator, which has been used for motion correction and shown not to interfere with DWI collection, has been inserted after each DWI volume for BOLD measurement. For faster temporal sampling, we also test the inclusion of a second 3D EPI navigator in the middle of each DTI volume acquisition. Resting state networks produced in the standard BOLD and double navigated DTI-fMRI showed quite similar spatial extent and connectivity. Diffusion data produced similar whole brain distributions of tensor parameters, as well as strikingly similar tractographic reconstructions.

2111.   Local intrinsic connectivity measures relate to GABA/Glx levels
Katarzyna Bienkowska1 and Valentin Riedl1
1Neuroradiology, Technische Universitat Munchen, Munich, Germany

In presented study, a combined fMRI-MRS study has been performed to examine interactions between GABA/Glx levels and local intrinsic brain activity (iFC). Recently there has been considerable progress done in investigating interactions between GABA level and BOLD signal change during visual stimulation. What has not been carefully studied yet is the relationship between resting state coherent BOLD signal change (functional connectivity) and excitatory/inhibitory neurotransmitter balance. Therefore, GABA and Glx concentration in the occipital cortex were correlated with local functional connectivity (lFC) and amplitude of low frequency fluctuations (ALFF) of the resting brain in eyes-open and eyes-closed condition.

2112.   Mapping epileptic networks using simultaneous EEG-MRI at ultra-high field
Frédéric Grouiller1, João Jorge2,3, Francesca Pittau4, Pascal Martelli1, Wietske van der Zwaag5, Christoph M. Michel6, Serge Vulliémoz4, Maria Isabel Vargas1, and François Lazeyras1
1Department of Radiology and Medical Informatics, Geneva University Hospital, Geneva, Switzerland, 2Department of Bioengineering, Institute for Systems and Robotics, University of Lisbon, Lisbon, Portugal, 3Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 4EEG and Epilepsy Unit, Department of Neurology, Geneva University Hospital, Geneva, Switzerland, 5Biomedical Imaging Research Center (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 6Functional Brain Mapping Laboratory, University of Geneva, Geneva, Switzerland

We report the feasibility to record simultaneous EEG-fMRI at 7T in epileptic patients. We successfully located epileptic networks using an optimized setup to reduce environmental noise and appropriate artefacts removal algorithms. The quality of intra-MR EEG allows detecting interictal epileptiform discharges and performing noise-sensitive topography-related analyses to detect epilepsy-specific haemodynamic changes. These results open new perspectives to better characterize epileptic networks at higher field.

2113.   BOLD correlate of spontaneous cortical and thalamic slow oscillations
Florian Schmid1, Miriam Schwalm2, Lydia Wachsmuth1, Cornelius Faber1, and Albrecht Stroh2
1Department of Clinical Radiology, University of Münster, Münster, Germany, 2Institute of Microscopic Anatomy and Neurobiology, Johannes Gutenberg-University Mainz, Mainz, Germany

We investigated the BOLD correlate of locally detected Ca2+-recordings of spontaneous cortical and thalamic slow oscillations in rats and found BOLD activation of the cortex correlated to both cortical and thalamic up-states.

2114.   Micro- and macrovascular contributions to layer-dependent blood volume fMRI: a multi-modal, multi-species comparison
Laurentius Huber1, Jozien Goense2, Aneurin Kennerley3, Maria Guidi1, Robert Trampel1, Robert Turner1, and Harald E Möller1
1Max Planck Institute for Human Cognitive & Brain Sciences, Leipzig, Germany, 2University of Glasgow, United Kingdom, 3University of Sheffield, United Kingdom

This study investigates cortical layer-dependent functional changes of cerebral blood volume (CBV) in humans, monkeys and rats at 7 T. Using multiple imaging modalities including vascular space occupancy (VASO), iron-oxide contrast agent based fMRI, and optical imaging spectroscopy, we investigated the contributions of pial macrovasculature and layer-specific microvasculature to CBV based fMRI signals. Based on the results presented here, we suggest that the pial macrovasculature can introduce amplifying or attenuating signal contributions to layer-dependent CBV responses. These contaminations manifest themselves differently, depending on the units (ml or %) used in the evaluation procedure.

2115.   Simultaneous Electroencephalography and Pseudo-Continuous Arterial Spin Labelling Measurements: Feasibility Study
Qingfei Luo1, Chung-Ki Wong1, Han Yuan1, Vadim Zotev1, Wen-Ming Luh2, and Jerzy Bodurka1,3
1Laureate Institute for Brain Research, Tulsa, OK, United States, 2Cornell MRI Facility, Cornell University, Ithaca, NY, United States, 3College of Engineering, Center for Biomedical Engineering, University of Oklahoma, Norman, OK, United States

Pseudo-continuous arterial spin labeling (PCASL) is a quantitative CBF-fMRI pulse sequence. We investigate feasibility of simultaneous electroencephalography (EEG) and PCASL multi-modal measurement. Specific absorption rate (SAR) of PCASL, may increase the temperatures of EEG electrodes and thus have potential safety risks. To evaluate the feasibility and safety we performed real-time measurements of EEG electrode temperatures during concurrent EEG&PCASL (acquired with standard imaging hardware) at 3 Tesla. The results showed that the electrode temperature after a long PCASL scan will reach about 34°C - well below the safety limit (41°C). Results show feasibility of multi-modal EEG&PCASL experiments.

2116.   Differences in the resting-state fMRI global signal amplitude between the eyes open and eyes closed states are related to changes in EEG vigilance
Chi Wah Wong1 and Thomas Liu1
1Center for Functional MRI, University of California San Diego, La Jolla, CA, United States

The amplitude of the resting-state fMRI global signal was compared between eyes open (EO) and eyes closed (EC) states. The amplitude of the global signal was significantly lower in the EO state and the magnitude of the decrease was correlated with increases in EEG vigilance. The relation between the EO-EC changes in global signal amplitude and EEG vigilance was found to be similar to that previously observed for caffeine-related changes in global signal amplitude and vigilance.

2117.   Map the light-driven fMRI signal in combination with in vivo recording
Maosen Wang1, Yi He1, Yaohui Tang1, Dávid Zsolt Balla2, Chunqi Qian3, and Xin Yu1
1Research Group of Translational Neuroimaging and Neural Conteol,High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tuebingen, Baden-Wuerttemberg, Germany, 2Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tuebingen, Baden-Wuerttemberg, Germany,3Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Str, National Institutes of Health, Bethesda, MD, United States

It remains ambiguous how the direct fiber optic insertion affects the local fMRI signal by optical stimulation. The fiber optic was inserted to target the deep layer cortex expressing Channelrhodopsin 2(ChR2). Robust fMRI signal was detected in the cortical regions close to the fiber tip with varied light pulse parameters on frequency, pulse duration and power level. The light evoked local field potential was also recorded by electrodes inserted into the cortex expressing ChR2. This work provides us a robust light-driven fMRI platform in combination with in vivo recording, which will facilitate the study to decipher cellular contribution to fMRI signal from the local neurovascular network.

2118.   Investigating the role of interictal activity during a natural stimulus presentation in children with epilepsy
Elhum A Shamshiri1, Maria Centeno1, Tim Tierney1, Kelly St Pier2, Ronit Pressler2, Suejen Perani1,3, Helen J Cross4, and David W Carmichael1
1Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom, 2Epilepsy Unit, Great Ormond Street Hospital, London, United Kingdom, 3Department of Basic and Clinical Neurosciences, Institute of Psychiatry, Psychology, and neuroscience, London, United Kingdom, 4Neurosciences Unit, University College London, London, United Kingdom

Previously, cognitive network aberrations have been shown in epilepsy patients with regards to resting state networks such as the DMN (default mode network). However, the influence of interictal activity on these networks has yet to be properly explored. This study uses EEG-fMRI to explore the effect of spikes as a regressor of no interest in cognitive networks using a general linear model (GLM) and functional connectivity.

2119.   On the feasibility and specificity of simultaneous EEG and ASL MRI at 3T
Elise Bannier1,2, Marsel Mano2,3, Robert Stroemer4, Isabelle Corouge2, Lorraine Perronnet2,3, Jussi T. Lindgren3, Anatole Lecuyer3, and Christian Barillot2
1Radiology, University Hospital of Rennes, Rennes, France, 2Unité VISAGES U746 INSERM-INRIA, IRISA UMR CNRS 6074, University of Rennes, Rennes, France, 3Unité HYBRID INRIA, IRISA UMR CNRS 6074, Rennes, France, 4Brainproducts GmbH, Gilching, Germany

The aim of the study was to assess the feasibility and specificity of simultaneous ASL MRI and EEG recording at 3T in terms of safety, EEG and MR signal quality.

2120.   Bold Oxygen Level Dependant (BOLD) Quantitative Susceptibility Mapping (QSM) at Different Head Orientations
M Ethan MacDonald1,2, Avery Berman2,3, Rebecca J Williams1,2, Erin L Mazerolle1,2, and G Bruce Pike1,2
1Radiology and Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada, 2Hotchkiss Brain Institute, Foothills Medical Centre, Alberta Health Services, Calgary, Alberta, Canada, 3Biomedical Engineering, McGill University, Montreal, Quebec, Canada

In this work, we use a quantitative susceptibility technique calculated from the phase data from BOLD-fMRI. Measurements of the susceptibility time course (BOLD-QSM) are compared to BOLD-fMRI in visual and motor regions. Subject’s heads are moved and imaging is repeated. Contrast to noise ratio is calculated in the signals from both techniques and found to be comparable. Five of eight measured signals showed higher CNR with the BOLD-QSM method. A good level of correlation is obtained between the two methods.

2121.   Assessment of the Reproducibility of BOLD signal-based Hemodynamic MRI
Toshihiko Aso1 and Hidenao Fukuyama1
1Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan

Mapping of temporal delay in rs-fMRI signal is potentially useful as a contrast agent-free hemodynamic imaging. Our test-retest reliability study revealed that time-lag, magnitude and maximum-Z maps all have higher consistency than a functional connectivity map. Particularly the striking day-to-day stability encourages use of this technique for longitudinal observation in patients.

2122.   Brain Atrophy Accounts for Age-Related Differences in Hemodynamic Impulse Response Function from Auditory Cortex
Raphael T Gerraty1, David B Parker2, Alayar Kangarlu3, and Qolamreza R Razlighi2,4
1Psychology, Columbia University, New York, NY, United States, 2Biomedical Engineering, Columbia University, NY, United States, 3Psychiatry, Columbia University, NY, United States, 4Neurology, Columbia University, New York, NY, United States

Hemodynamic Impulse Response Function varies across life span; however we showed that brain atrophy and inaccurate co-registration accounts for most of these age related variabilities.

2123.   Hemodynamic Response Pattern upon Noxious Electrical Stimulation in Rat Models of Pain
Saeedeh Amirmohseni1, Daniel Segelcke2, Esther Pogatzki-Zahn2, and Cornelius Faber1
1Department of Clinical Radiology, University Hospital Muenster, Muenster, Germany, 2Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany

In human fMRI studies, BOLD response to constant painful electrical and thermal stimulation has shown deviations from the canonical hemodynamic response function, leading to possible false negatives in activation maps when using a boxcar analysis model. In this work, we have considered possible signal variations during the BOLD response in the analysis, to process the data of noxious electrical stimulation of the hindpaw in rat models of incisional and inflammatory pain, and demonstrated the importance of accounting for these variations in order to fit the actual shape of the BOLD response.

2124.   Underestimation of functional connectivity with impaired cerebrovascular reserve : a working model of moyamoya disease
Tzu-chen Yeh1,2, Chou-ming Cheng3, Jin-jie Hong2, Sheng-che Hung1, Muh-Lii Liang4, and Jen-chuen Hsieh2,3
1Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan, 2Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, Taiwan,3Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan, 4Neurosurgery Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan

Impaired cerebrovascular reserve (CVR) was supposed to cause dissociation between functional integrity and functional connectivity due to regional variation of CVR. And reversed linearity between functional connectivity and carbogen-based CVR suggested enhanced or neuroplasticity in patients of moyamoya disease. Underestimated or aberrant FC should be considered with impaired CVR, and studies of FC in diseased states need evidence of preserved CVR.

2125.   The impact of echo time on the calibration parameter M
Hannah Hare1 and Daniel Bulte1
1FMRIB, University of Oxford, Oxford, Oxon, United Kingdom

A calibrated BOLD experiment was performed with a multi-echo sequence to determine how BOLD response to hypercapnia and the calibration parameter M vary with echo time. Theory has predicted these relationships to be directly proportional, but is based on the assumption of negligible intravascular signal contribution. We performed experiments both with and without the use of intravascular crushers, and show that although M is a linear function of echo time, the intercept is not zero. This result has implications for the commonly employed scaling method used to better compare M values from experiments with differing echo times.

2126.   
Age-related differences in CBF, CVR, M, OEF and CMRO2 using MRI QUO2 and dual-echo pCASL
Isabelle Lajoie1, Kenneth S Dyson2, Scott Nugent2, Felipe D Tancredi1,3, and Richard D Hoge2
1Centre de recherche de l'IUGM, Université de Montréal, Montreal, Quebec, Canada, 2McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada, 3Albert Einstein Jewish Hospital, Brazil

It is believed that the delivery and consumption of oxygen have an important role in the pathogenesis of conditions such as Alzheimer’s Disease (AD), rising the pertinence of developing technologies that provide such information. We demonstrate here the potential of the MRI method introduced in our team, dubbed QUO2, for characterizing age-related differences in cerebral physiology, more precisely in resting CBF, CVR, M, OEF and CMRO2. In the next step, we will use our protocol to evaluate the level of discrepancy between individuals diagnosed with AD and age-matched controls.

2127.   Investigating the effect of hyperoxia and hypercapnia on T2* and S0 calculated from multi-echo BOLD data at 7T.
Alex A Bhogal1, Jeroen C.W. Siero2, Marielle E. Philippens2, Esben T. Petersen2, Martijn Froeling2, Jeroen Hendrikse2, Manus J. Donahue3, and Hans Hoogduin2
1University Medical Center, Utrecht, Utrecht, Netherlands, 2University Medical Center, Utrecht, Netherlands, 3Vanderbilt University School of Medicine, Tennessee, United States

Hypercapnia and hyperoxia, induced using targeted gas challenges, may be used to probe physiological effects related to the Blood Oxygen Level Dependent (BOLD) signal. Multi-echo BOLD data is acquired allowing changes in T2* and S0 parameters in response to breathing challenges to be examined. Results are explained in the context of physiological phenomenon.

2128.   Physiological Modulators of Resting-State MRI Functional Connectivity
Powell Pui Wai Chu1,2, Ali M. Golestani1, Jonathan B. Kwinta1,2, Yasha B. Khatamian1, and Jean J. Chen1,2
1Rotman Research Institute, Baycrest, Toronto, Ontario, Canada, 2Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Resting-state fMRI functional connectivity (rs-fcMRI) measurements are based on the BOLD fMRI signal, which is influenced by systemic physiological variability. Thus, fcMRI data interpretation may be difficult across different subjects without the knowledge of these physiological influences. In this work, in order to improve the reliability of rs-fcMRI measurements, we assess the influence of physiological factors including baseline cerebral blood flow and venous blood oxygenation on functional connectivity estimates. We found a significance relationship between rs-fcMRI values and the above two physiological variables.

2129.   Test-retest reproducibility of the BOLD response to a hypercapnic challenge
Bryon A. Mueller1, Nicholas Evanoff2, Kara L. Marlatt2, Justin R. Geijer3, Kelvin O. Lim1, and Donald R. Dengel2
1Department of Psychiatry, University of Minnesota, Minneapolis, MN, United States, 2School of Kinesiology, University of Minnesota, Minneapolis, MN, United States,3Department of Health, Exercise and Rehabilitative Sciences, Winona State University, Winona, MN, United States

BOLD imaging during a hypercapnic challenge is often used to measure cerebral vascular reactivity. Determining the within and between day reproducibility of the BOLD signal change in response to a reproducible hypercapnic challenge will help determine if this method is precise enough to be used as a research tool to compare specific groups to control populations. We have measured the intraclass correlation coefficient and coefficient of within-subject variation for BOLD imaging during an iso-oxic, hypercapnic square stimulus. Results show excellent within day reproducibility and good between day reproducibility within the cerebral gray matter.

2130.   The susceptibility of dissolved oxygen
Avery J.L. Berman1,2, Yuhan Ma1, Richard D. Hoge1,3, and G. Bruce Pike1,2
1Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada, 2Department of Radiology/Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, 3Unité de neuroimagerie fonctionelle, Centre de recherche de l'institut de gériatrie de Montréal, Montreal, Quebec, Canada

The susceptibility of dissolved O2 in blood was studied, focusing on the implications for BOLD imaging using hyperoxia. We proposed a model for the susceptibility of blood that incorporates dissolved O2 and compared it with another previously proposed model. Distilled water and samples of bovine plasma were oxygenated and their susceptibilities were determined using gradient echo phase imaging. Measured changes in susceptibility vs. O2 concentration were linear, with slopes that were dramatically less than previously predicted and in good agreement with our model. Under most physiological conditions, the susceptibility of dissolved O2 can be disregarded in MRI studies employing hyperoxia.

2131.   A Bayesian framework for the estimation of OEF by calibrated MRI
Michael Germuska1, Alberto Merola1, Alan Stone2, Kevin Murphy1, and Richard Wise1
1Cardiff University, Cardiff, Wales, United Kingdom, 2Oxford University, Oxfordshire, United Kingdom

Recently, calibrated MRI methods of estimating resting oxygen extraction fraction (OEF) have been developed. These methods rely on the independent quantification of BOLD and blood flow responses to respiratory challenges. The resulting estimates are then fed into a physiological model to solve for OEF. Data analysed in such a step-wise manner are susceptible to the propagation of errors along the pipeline, producing unstable estimates of OEF. Here we re-pose the analysis in a Bayesian framework to solve for the underlying physiological parameters in a one-step solution. In-vivo data demonstrates stable estimates of OEF within the expected range for healthy tissue.

2132.   Linear dependence of neuronal oscillations on hypercapnia level: implications for CO2 calibrated fMRI
Ian D Driver1, Joseph Whittaker1, Molly G Bright1, Suresh D Muthukumaraswamy1,2, and Kevin Murphy1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom, 2Schools of Pharmacy and Psychology, Auckland University, Auckland, New Zealand

Understanding the effect of hypercapnia on neuronal oscillations and cerebral metabolism is an important consideration for physiological and calibrated fMRI studies. Here we use MEG measurements to study broadband neuronal desynchronisation during graded levels of hypercapnia. Neuronal desynchronisation persisted even in mild levels of hypercapnia, below the sensory threshold (subjects performed a breathlessness rating task). There appears to be a linear dependence of the neuronal desynchronisation on the level of hypercapnia, presenting a possible solution for hypercapnia calibrated fMRI to overcome the violation of the isometabolic assumption with hypercapnia.

2133.   Measurement of oxygen extraction fraction (OEF): an optimised BOLD signal model for use with hypercapnic and hyperoxic calibration
Alberto Merola1, Kevin Murphy1, Alan J Stone1, Michael A Germuska1, Valerie E M Griffeth2, Nicholas P Blockley3, Richard B Buxton3,4, and Richard G Wise1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom, 2Department of Bioengineering and Medical Scientist Training Program, University of California San Diego, La Jolla, California, United States, 3Center for Functional Magnetic Resonance Imaging, Department of Radiology, University of California San Diego, La Jolla, California, United States, 4Kavli Institute for Brain and Mind, University of California San Diego, La Jolla, California, United States

In this simulation study we analyze an existing mathematical model for BOLD calibration and assessment of oxygen extraction fraction (OEF). We have generated datasets of synthetic BOLD signals arising from a wide range of simulated physiological conditions and a variety of hypercapnic and hyperoxic respiratory tasks. OEF estimates demonstrate the inaccuracy of the current model and let us proposing a new approach for optimizing it. We were then able to optimize the current model and propose a new simplified model, achieving greatly improved performances. This represents a significant step forward towards an accurate and reliable quantification of oxygen metabolism in brain.

2134.   Changes in CBF/CMRO2 coupling with graded visual stimuli are modulated by baseline perfusion
Joseph Whittaker1, Ian Driver1, Molly Bright1, and Kevin Murphy1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom

The BOLD fMRI response depends on multiple physiological factors, in particular, the ratio of fractional changes in CBF and CMRO2, defined as n. Meaningful comparisons of BOLD responses between stimulus conditions rely upon a constant n, which may not be the case. The BOLD and CBF responses to 4 visual contrast levels were measured in 9 subjects during normocapnia and hypercapnia. We found larger BOLD responses during hypercapnia, suggesting altered CBF/CMRO2 coupling dynamics. These data show BOLD changes that are consistent with varying n values across contrast, and which are modulated further by changes in baseline physiology.

2135.   An optimised respiratory paradigm for the Bayesian estimation of OEF by calibrated MRI
Michael Germuska1, Alberto Merola1, Kevin Murphy1, and Richard Wise1
1Cardiff University, Cardiff, Wales, United Kingdom

The estimation of the resting oxygen extraction fraction (OEF) has been demonstrated by calibrated measurement of the BOLD signal with serial hypercapnic and hyperoxic stimuli. However, the optimal respiratory paradigm (number, timing and duration of stimuli) has yet to be investigated. Here we utilise a detailed signal model and a realistic physiological noise model to optimise such a paradigm for the estimation of OEF. Our results suggest that the derived paradigm offers a significant improvement in the accuracy of OEF estimates compared to previously implemented designs of the same (18 minute) duration.

2136.   Investigation of neurovascular coupling within brain by simultaneous recordings of LFP and fiber-optic hemodynamic signals
Wen-Ju Pan1, Jacob Billings1, and Shella Keilholz1
1Biomedical Engineering, Emory University/ Georgia Institute of Technology, Atlanta, Georgia, United States

Intrinsic optical spectroscopy (IOS) may provide multiple hemodynamic parameters in high time resolution in functional optical imaging but rarely used within brain study. We developed a combination of optic fiber-based IOS, ~100um in diameter, and microelectrode neuronal LFP signal recording within brain at similar spatial range, a few hundred micros. This simultaneous recording design may be a promising approach for examining target sites of neurovascular coupling relations in brain.

2137.   Simultaneous Voxel-wise Mapping of Oxygen Extraction Fraction, Blood Flow and Cerebral Metabolic Rate of Oxygen
Yongxia Zhou1, Zachary B Rodgers1, and Felix W Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

An integrated MRI protocol was developed for simultaneous mapping of CBF with acceleration-based ASL and OEF with GESFIDE. The GESFIDE module was integrated into the post-label delay control module of the ASL sequence and total scan time was 405sec. Preliminary results in eight subjects, after averaging of data across the brain and subjects yielded values of 47.7±4.8mL/100g/min, 32.7±2.6%, and 123.8±11.1µmol/100g/min for CBF, OEF and CMRO2, respectively, in good agreement with the literature. Positive correlations between CBF and CMRO2 and negative trend between CBF and OEF were found. Global CMRO2 value correlated significantly with other established methods for the same subjects.

2138.   Effect of noise regression on ASL based functional connectivity
Kay Jann1, Edgar A Rios Piedra1, Robert X Smith1, and Danny JJ Wang1
1Department of Neurology, University of California Los Angeles, Los Angeles, California, United States

Noise-regression in BOLD-fMRI is necessary to minimize influences of motion, heart rate and respiration on functional connectivity (FC). Recently, modern pseudo-continuous ASL (pCASL) sequences have been shown to provide comparable FC networks as BOLD. However, the influence of head motion and physiological noise on ASL-FC has not yet been investigated. Here we report effects of different noise-regression strategies on FC using 2D-EPI and 3D-BS-GRASE pCASL. We found that ASL-FC analyses are feasible especially for 3D-BS-GRASE pCASL, but proper noise regression is still mandatory to prevent erroneous findings related to motion or physiological noise.

2139.   MR Perfusion Imaging Using High-Temporal-Resolution Resting-State Functional Magnetic Resonance Imaging
Tianyi Qian1, Yinyan Wang2,3, and Tao Jiang2,3
1MR Collaborations NE Asia, Siemens Healthcare, Beijing, Beijing, China, 2Beijing Neurosurgical Institute, Beijing, China, 3Beijing Tiantan Hospital, Capital Medical University, Beijing, China

In previous resting-state functional magnetic resonance imaging (rs-fMRI) studies, the global signal (the averaged time series of BOLD signal across the whole brain) has always been treated as the background noise and is typically regressed out. Here, an iterative algorithm was used to extract the time-shift-corrected global signal. By calculating the time delay and weight with respect to the corrected global signal in each voxel, we were able to measure the transient time of the whole brain. Simultaneous multislice acceleration acquisition combined with rs-fMRI was used to acquire the dataset used in this study to further improve the temporal and spatial resolution of this method.