Electronic Poster Session - fMRI
  fMRI: Connectivity Analysis & Temporal Characteristics 2820-2843
  fMRI: Analysis & High-Resolution Methods 2844-2867
  fMRI: Connectivity Analysis & Novel Contrasts 2868-2891
  fMRI: Neuroscience Applications & Brain Physiology 2892-2915

fMRI: Connectivity Analysis & Temporal Characteristics
Click on to view the abstract pdf and click on to view the video presentation. (Not all presentations are available.)
Monday 7 May 2012
Exhibition Hall  10:45 - 11:45

  Computer #  
2820.   49 A geometric view of global signal confounds in resting-state fMRI
Thomas Liu1, and Hongjian He2
1UCSD Center for Functional MRI, La Jolla, CA, United States, 2Bio-X Laboratory, Zhejiang University, Hangzhou, China

In resting-state functional connectivity MRI (fcMRI), the presence of global signal confounds lead to variability in connectivity maps. A number of global signal correction methods have been proposed, but have their limitations. Here we demonstrate that a portion of the global signal can be viewed as an additive confound that increases with the mean BOLD amplitude. An approach for minimizing the contribution of this additive confound is presented, and an initial comparison with existing global signal correction methods is provided.

2821.   50 Noise-related variance of functional networks
Hu Cheng1, and Aina Puce1
1Indiana University, Bloomington, IN, United States

A simple method is proposed to estimate the variance of resting state functional network originated from residual noises in the MRI signal. The variance from noise is compared with the total variance between networks from different time periods. The results suggest that a substantial amount of variance of the functional network comes from the intrinsic noise that is not coupled with the coherences of different brain regions. Sampling more time points can effectively reduce the noise-related variance. Another effect of residual noise is reduction of the correlation coefficient, which can be estimated from the variance of network.

2822.   51 Identification of state changes from spontaneous fluctuations in fMRI data
Meghan Robinson1, Javier Gonzalez-Castillo1, Souheil Inati2, Daniel Handwerker1, and Peter Bandettini1,2
1Section on Functional Imaging Methods, NIMH, NIH, Bethesda, MD, United States, 2functional MRI Facility, NIMH, NIH, Bethesda, MD, United States

The brain is continuously adapting to respond to the environment. In the course of a rest scan, subjects are expected to engage in different cognitive states for variable periods of time (i.e., relaxing, planning dinner, napping, etc.). Each of these states brings the brain into a different pattern of overall connectivity. Still, some level of stability is expected for the periods when subjects remain in a given cognitive state. Here, we propose a way to automatically identify such cognitive states looking at how the fMRI signal from different cortical regions pass in-and-out of synchrony with each other as time progresses.

2823.   52 Time-Frequency Dynamics of Resting State Effective Connectivity in the Default Mode Network
Gopikrishna Deshpande1,2, Hao Jia1, Zhihao Li3, and Xiaoping Hu3
1AU MRI research center, Dept. of ECE, Auburn University, Auburn, Alabama, United States, 2Dept. of Psychology, Auburn University, Auburn, Alabama, United States, 3Coulter Dept of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States

Functional connectivity in resting state networks show dynamic patterns in time and frequency.We hypothesized that effective connectivity between resting state fMRI time series may also dynamically evolve across time and frequency. We obtained effective connectivity between 33 regions in 4 RSNs as a function of time and frequency using dynamic multiscale vector autoregressive model based on Kalman filter. We observed that in the 0.1 to 0.01 Hz frequency range, RSNs toggle between 5 distinct states.

2824.   53 Observing Resting-State Networks at Higher Frequencies with MR-Encephalography and Independent Component Analysis
Hsu-Lei Lee1, Benjamin Zahneisen1, Thimo Hugger1, Pierre LeVan1, and Jürgen Hennig1
1Medical Physics, University Medical Center Freiburg, Freiburg, Germany

MR-Encephalography allows the acquisition of whole brain volume image within 100 msec. With this high sampling rate, we looked at resting-state fMRI BOLD signal at 0.5~0.8 Hz. Independent component analysis revealed several resting-state networks that are similar to the ones observed under 0.1 Hz. These networks at higher frequencies are more stable as we shorten the signal length, therefore can provide the possibility to shorten total scan time and to assess resting-state network dynamics over a period of time.

2825.   54 Unsupervised Parcellation of Precentral Gyrus using Resting-state fMRI
Ali-Mohammad Golestani1, and Mariana Lazar1
1Radiology, New York University Medical Center, New York, NY, United States

Anatomical landmarks are commonly used to identify regions of interest (ROIs) for brain imaging studies that might not reflect functional specialization. Previous studies showed that some of the anatomically defined ROIs can be subdivided into sub-regions based on their connectivity. Most of the parcellation approaches use clustering algorithms in which the number of clusters should be known in advance. We used a new clustering method that estimates the number and size of sub-regions, and parcellate precentral gyrus into posterior and inferior parts. This study highlights the importance of using a parcellation method that can automatically detect the number of clusters.

2826.   55 Functional Connectivity Based Clustering of White Matter
Clare Kelly1, Greg J. Siegle2, and Michael P. Milham3,4
1NYU Child Study Center, New York, NY, United States, 2University of Pittsburgh School of Medicine, Pittsburgh, PA, United States, 3Nathan S. Kline Institute for Psychiatric Research, NY, United States, 4Child Mind Institute, New York, NY, United States

Studies applying clustering methods to intrinsic (resting-state) functional connectivity (iFC) data have largely avoided white matter (WM), reflecting skepticism regarding the fidelity of WM BOLD signal. In light of mounting evidence supporting the neurophysiological veracity of WM BOLD, we parcellated WM on the basis of iFC, using a multi-site large-n dataset. We obtained a symmetrical topography consistent with DTI tractography atlases. For example, the corpus callosum, the internal capsule, and the superior longitudinal fasciculus were stably identified across sites. We suggest that iFC measures may have utility for the investigation of WM in clinical disorders characterized by WM alterations.

2827.   56 BrainNet Viewer: A Graph-Based Brain Network Mapping Tool
Mingrui Xia1, Jinhui Wang1, and Yong He1
1State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China

With the development of complex network analyzes on human brain neuroimaging data; visualization of the structural and functional connectivity patterns became an important part of the graph theoretical approach. An easy using network visualization tool can help researchers show their results intuitively, and highlight their key point. Therefore we developed this brain network visualization tool termed as ‘BrainNet Viewer’, which can help researchers visualize structural and functional connectivity patterns from different levels in a quick, easy and flexible way. This package can be downloaded from NITRC (www.nitrc.org/projects/bnv/).

2828.   57 The x-Guided Clustering Method and its Application to Unbiased Detection of Differences in Functional Connectivity Networks
Gang Chen1, B. Douglas Ward1, Chunming Xie1, Wenjun Li1, Guangyu Chen1, Joseph S Goveas2, Piero G Antuono3, and Shi-Jiang Li1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, 2Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, WI, United States, 3Neurology, Medical College of Wisconsin, Milwaukee, WI, United States

In resting-state functional MRI cross-group studies, the available techniques may bias the results in choosing the specified reference. We introduced an x-guided clustering method to solve this problem. The x-guided clustering method incorporates all of the subject groups by producing group difference information and then creating functional clusters. This method was applied to identify functional clusters that were significantly different between the amnestic mild cognitively impaired and cognitively normal subjects.

2829.   58 A new information theoretic approach to quantify fMRI functional connectivity
Yinan Liu1, Karl Young1,2, Yu Zhang1,2, Michael Weiner1,2, and Norbert Schuff1,2
1Department of Veteran Affairs Medical Center, Center for Imaging of Neurodegenerative Diseases, San Francisco, CA, United States, 2Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, United States

We examined the value of transient information (TI), a recently introduced information-theoretic quantity that measures the uncertainty in synchronization, for characterizing functional connectivity in fMRI. Specifically, we used TI to capture the process of synchronization between two fMRI signals whose periodicity is initially unknown. We found that TI various markedly across the brain with e.g. posterior cingulate and precuneus synchronizing easier and faster with each other than with the putamen. These preliminary results suggest that TI may be a useful metric for quantifying functional connectivity.

2830.   59 A Comparison Study of CMBHC and ICA Methods for Human Functional Connectivity Analysis
Xiao Liu1, Xiao-Hong Zhu1, and Wei Chen1
1Radiology, Center for Magnetic Resonance Research, Minneapolis, MN, United States

In this study, a recently proposed correlation-matrix-based hierarchical clustering (CMBHC) method was tested and evaluated using human resting-state fMRI datasets, and the results were compared with those obtained using the independent component analysis (ICA). It was found that the CMBHC was able not only to extract more coherent patterns than the ICA, but also to retain a number of weak but consistent functional connections (e.g., cortico-subcortical connections) that were largely missed by the ICA. The overall results suggest that the CMBHC could be a powerful tool for analyzing resting-state fMRI data, especially at the single subject level.

2831.   60 A wavelet-based approach to improve the reproducibility of resting-state fMRI analysis
Shantanu Majumdar1, and David C Zhu1,2
1Department of Radiology, Michigan State University, East Lansing, Michigan, United States, 2Department of Psychology, Michigan State University, East Lansing, Michigan, United States

Resting-state fMRI has shown great potential towards understanding the spontaneous brain activity at rest in healthy subjects as well as patients with neurological disorders. A viable clinical tool requires a high level of reproducibility. In this work, we investigated quantitative effects of a wavelet-based analysis of resting-state fMRI signal to improve the reproducibility in detecting functionally active brain regions.

61 Non-linear modulation of both positive and negative fMRI responses to visual stimulation by pre-stimulus occipital EEG alpha power
Stephen D Mayhew1, Camillo Porcaro2, Dirk Ostwald3, and Andrew P Bagshaw1
1Birmingham University Imaging Centre, School of Psychology, University of Birmingham, Birmingham, West Mids, United Kingdom, 2Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom, 3Bernstein Centre for Computational Neuroscience, Berlin, Germany

We use simultaneous EEG-fMRI to investigate the relationship between ongoing or "baseline" brain activity, as indexed by pre-stimulus EEG alpha (8-13Hz) power, and the magnitude of the BOLD fMRI response to brief visual stimulation. We report a significant reduction of visual PBR and enhancement of auditory NBR in trials preceded by high alpha power, beyond that predicted by a linear model. This study provides new evidence that both PBR and NBR to visual stimulation are nonlinearly dependent upon electrophysiological characteristics of baseline brain activity and that NBR reflects inhibition of non-task related brain areas as indexed by occipital alpha power.

2833.   62 Analysis of MR Signal Dynamics during Carbogen Inhalation using a Combined Spin- And Gradient-Echo (SAGE) EPI Sequence
Georges Hankov1, Thomas Christen1, Heiko Schmiedeskamp1, Roland Bammer1, and Greg Zaharchuk1
1Department of Radiology, Stanford University, Stanford, California, United States

The purpose of the study was to follow and analyze the dynamic changes in brain oxygenation induced by a carbogen respiratory challenge in normal human brain. Using a simple model and a multiple spin- and gradient-echo (SAGE) EPI sequence, maps of amplitude, wash-in and wash-out time constants, and arrival time delay of carbogen were computed. In 5 volunteers, we found a homogeneous response to carbogen and low inter-subject variability. This methodology could be used to study pathologies such as stroke or cancer.

2834.   63 The Contribution of Vascular Reactivity in Layer-Specific Hemodynamic Response
Cecil Chern-Chyi Yen1, Fuqiang Zhao2, and Seong-Gi Kim3,4
1National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States, 2Imaging, Merck, West Point, PA, United States, 3Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 4Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States

Cortical layer-specific responses are shown to resemble the neural response of the cortical layers. However, these layer-specific hemodynamic responses may be contaminated by the vascular reactivity, which is known to have layer-specific distribution. To investigate this issue, we performed two cerebral blood volume (CBV)- weighted fMRI studies in cat visual cortex with hypercapnic stimulus as an indicator for vascular reactivity, and visual stimulus. Our results showed that the peak responses of the CBV-weighted layer profile induced by hypercapnic stimulus co-localized with that induced by visual stimulus. Therefore, cautions shall be taken in interpreting layer-specific hemodynamic response as neural response.

2835.   64 Specificity and Sensitivity of Layer specific fMRI responses using GE and 3D GRASE at high fields.
Federico De Martino1,2, Jan Zimmermann2, Lars Muckli3, Kamil Ugurbil1, Pierre-Francois van de Moortele1, Rainer Goebel2, and Essa Yacoub1
1Radiology, Center for Magnetic Resonance Research, Minneapolis, Minnesota, United States, 2Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 3Psychology, University of Glasgow, GLasgow, United Kingdom

Laminar specific fMRI in humans has potential for clinical applications. It has not yet been demonstrated whether gains in high field T2 weighted BOLD would be advantageous in layer specific fMRI investigations and/or in regions outside of V1. We examine layer specific response profiles in two different visual areas (V1 and MT) within the same subjects and compare Gradient Echo and GRASE. We show that GRASE might be preferred to GE when layer specific responses throughout the entire cortical depth are of interest.

2836.   65 An assessment of the post-stimulus undershoot using hyperoxic BOLD contrast and ASL
Ian D Driver1, Emma L Hall1, Paula L Croal1, Susan T Francis1, and Penny A Gowland1
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom

The BOLD post-stimulus undershoot (PSU) following a motor task is assessed at 7T through simultaneous measurement of BOLD, CBF, and venous CBV using hyperoxia. This work shows a post-stimulus undershoot in both the BOLD and CBF response, when the venous CBV response had returned to baseline. This suggests a neuronal origin for the PSU, but could also result from a delayed vascular compliance. Results show that at the spatial resolution (2 x 2 x 3 mm3), the PSU is not more localised to the underlying neuronal response, as reported in animal models.

2837.   66 Dynamic compartment-specific cerebral blood volume and BOLD responses to electrical forepaw stimulation in lower case Greek alpha-chloralose anesthetized rats
Xiaopeng Zong1, Tae Kim1, and Seong-Gi Kim1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States

Studying the compartment-specific dynamic cerebral blood volume responses is important for quantitative fMRI studies and understanding the dynamic properties of BOLD fMRI responses. In this study, we measured BOLD, arterial (Capital Greek DeltaCBVa), venous (Capital Greek DeltaCBVv), and total cerebral blood volume responses to electrical forepaw stimulation in lower case Greek alpha-chloralose anesthetized rats using a magnetization transfer-varied fMRI technique and injection of paramagnetic contrast agent. We found a fast Capital Greek DeltaCBVa response and a delayed slower Capital Greek DeltaCBVv response. Our findings are consistent with earlier studies under different anesthesia conditions and support the anesthesia independence of the fast CBVa and slow CBVv dynamic properties.

2838.   67 Dynamics of BOLD fMRI time series: dependence on cognitive load and sensitivity to temporal pre-processing
Catie Chang1, Biyu J. He2, and Jeff H. Duyn1
1Advanced MRI section, NINDS, National Institutes of Health, Bethesda, MD, United States, 2NINDS, National Institutes of Health, Bethesda, MD, United States

It was recently demonstrated that the BOLD signal exhibits scale-free temporal dynamics whose autocorrelation/long-range memory is reflected in the Hurst exponent (H). Here, we demonstrate that H and BOLD signal amplitude decrease as a function of increased cognitive effort (working memory load) across widespread regions of the brain. Furthermore, we characterize the sensitivity of H to the manner in which fMRI data are pre-processed. Importantly, removing noise due to physiological processes and head motion was found to enhance the significance of load-dependent changes in the Hurst exponent, increasing the likelihood that the observed dynamic changes are of neural origin.

68 Microvascular GE BOLD specificity and dynamics revealed by ultra high field MRI in humans
Jeroen C. W. Siero1,2, Nick F. Ramsey1, Hans Hoogduin1,2, Dennis W. J. Klomp2, Peter R. Luijten2, and Natalia Petridou1,2
1Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands

Gradient-echo BOLD at high fields has opened up the possibility to visualize the cortical columnar and laminar functional organization but its specificity can suffer from contributions of several vessel sizes even at high fields. Here we assess the microvascular contributions of the GE BOLD response (HRF) across the cortical depth at 7T by relating it to the microvascular specific SE BOLD response. We show that the early phase (onset time and rising slope) of the GE HRF is specific to the microvasculature in deep gray matter which presumably contains layers III-V.

2840.   69 Temporal Characteristics of the Homodynamic Response Function of Transition-band SSFP fMRI
Jing Chen1, Jing An2, Yan Zhuo1, and X. Joe Zhou3
1State Key Laboratory of Brain and Cognitive Science, Inst. of Biophysics, Chinese Academy of Sciences, Beijing, China, 2MR Collaboration NE Asia, Siemens Healthcare, Siemens Shenzhen Magnetic Resonance, Shenzhen, China, 3Department of Radiology and Center for MR Research, University of Illinois Medical Center, Chicago, IL, United States

Recently, steady-state free precession (SSFP) fMRI has drawn widespread interests, due to its unique ability of providing distortion-free functional images with improved SNR/CNR, especially in regions near susceptibility boundaries. However, to develop SSFP fMRI as a robust tool for a broad range of applications, several practical issues must be carefully examined. In this study, we measure the hemodynamic response function of transition-band SSFP (tb-SSFP) fMRI, describe its temporal characteristics, and evaluate its linearity.

2841.   70 Comparison of Methodologies for Detecting Small Temporal Differences in BOLD Responses Using fMRI
Santosh B. Katwal1,2, John C. Gore2,3, and Baxter P. Rogers2,3
1Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, United States, 2Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 3Biomedical Engineering, Vanderbilt University

We assessed the ability to detect small temporal differences in BOLD responses from fMRI using Granger causality. Task-related-voxels were selected using: i) self-organizing map (SOM), ii) independent component analysis (ICA), iii) statistical parametric mapping (SPM) and iv) localizer scan in conjunction with SPM. Additionally, we fitted curves to average signals with inverse logit functions and estimated the differences in time-to-peak to compare the temporal differences. The combination of SOM and Granger causality detected differences as small as 28 ms. In general, data-driven approach for voxel selection seems to work better than hypothesis-driven approach in detecting small temporal differences from fMRI.

2842.   71 Identification of Spatio-Temporal Oscillatory Signal Structure in Cerebral Hemodynamics Using DRIFTER
Simo Särkkä1, Arno Solin1, Aapo Nummenmaa1,2, Aki Vehtari1, Toni Auranen3, Simo Vanni3,4, and Fa-Hsuan Lin1,2
1Department of Biomedical Engineering and Computational Science, Aalto University, Espoo, Finland, 2Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 3Advanced Magnetic Imaging Centre, Aalto University, Espoo, Finland, 4Low Temperature Laboratory, Aalto University, Espoo, Finland

We use a Kalman filter and smoother method (DRIFTER) to identify physiological oscillatory signals from fMRI data, and analyze their spatial amplitude and phase structures. The frequencies of the cardiac and respiration signals were identified from external reference signals and the frequency of a physiological 0.1 Hz signal was identified from spatially averaged EPI data with 100 ms TR. The results indicate that the signals indeed have a clear spatial structure, which could be used to aid removal of the physiological signals or for analysis of brain functionality.

2843.   72 Correlated Slow Fluctuations in Respiration, EEG, and BOLD fMRI: What is the Origin of Physiological Noise?
Han Yuan1, Vadim Zotev1, Raquel Phillips1, and Jerzy Bodurka1
1Laureate Institute for Brain Research, Tulsa, OK, United States

We investigated the relationship between the respiration, alpha-band-limited EEG power, and BOLD fMRI from simultaneous recordings in human subjects and have found significant correlation between slow temporal fluctuations of these three sources of signals. In particular, the correlation between respiration and EEG is much stronger in closed-eye resting than in open-eye resting, and is consistently observed from recordings inside and outside scanner. Results suggest that respiration fluctuations reflect and are linked to the underlying brain electrophysiological activity.
Electronic Poster Session - fMRI

fMRI: Analysis & High-Resolution Methods
Click on to view the abstract pdf and click on to view the video presentation. (Not all presentations are available.)
Monday 7 May 2012
Exhibition Hall  11:45 - 12:45

  Computer #  
49 Approximate entropy as a metric for quantifying fMRI changes across time
Kyle D Steinke1, David Frakes2, Jose Rios3, Gabe Oland2, and Leslie C Baxter1
1Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States, 2School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, United States, 3Biomedical Engineering, Cornell University, Ithaca, NY, United States

Functional MRI is of limited utility in longitudinal studies because it lacks a quantitative baseline. We tested whether a test of interest (e.g., a motor task) could be compared to a generally stable vision task to overcome this weakness. We used approximate entropy (ApEn) to characterize each time series signal. The motor task ApEn was then compared to the vision task ApEn to form a ratio, which remained stable after a caffeine intervention, as expected, but changed in surgical patients that had behavioral decline.

2845.   50 A model of dopamine-induced fMRI response informed by simultaneous PET/fMRI
Joseph Mandeville1, Christin Sander2, Bruce Jenkins3, Bruce Rosen3, Jacob Hooker3, Ciprian Catana3, Wim Vanduffel3, Nathaniel Alpert3, and Marc Normandin4
1Radiology, Massachusetts General Hospital, Boston, MA, United States, 2Massachusetts Institute of Technology, United States, 3Radiology, Massachusetts General Hospital, United States, 4Massachusetts General Hospital, United States

fMRI data in an awake monkey during amphetamine challenge were acquired simultaneously with PET measurement of D2 receptor density. A compartment model of the fMRI response, based upon the competing effects of stimulation at D1 and D2 receptors, was developed to describe the temporal shape and magnitude of the fMRI response, while also accurately describing other reported fMRI responses in monkeys and rats at different levels of drug-induced dopamine. The model-inferred D2 contribution to fMRI signal correlated linearly with measured D2 receptor density. Simultaneous PET/MR measurements of dynamic dopaminergic function will be required to further refine the model.

2846.   51 Consistent Activation Across Trials and Field Strengths by ROC-reproducibility Thresholding
Tynan Reid Stevens1, David B Clarke2, Ryan CN D'Arcy1, and Steven D Beyea1
1IBD-Atlantic, NRC, Halifax, Nova Scotia, Canada, 2QEII Health Science Centre, Halifax, Nova Scotia, Canada

Setting activation thresholds remains a significant challenge in fMRI. Fixed threshold levels do not account for individual variability, habituation, or acquisition strategies. We developed a method for determining data-driven thresholds levels based on test-retest ROC-reproducibility (ROC-r) analysis. Eight subjects performed test-retest fMRI at two field strengths (1.5 & 4 Tesla). Optimized ROC-r thresholds were calculated for the template (5.27 +/- 0.22) and retest images (3.71 +/- 0.18). The ROC-r thresholds were significantly higher for 4 Tesla than 1.5 Tesla. Compared to FDR or Bonferroni thresholds, ROC-r thresholds produced more consistent activation extent across field strengths and trials.

2847.   52 fMRI Motion Regressors Based on EEG Motion Artifacts in Simultaneous EEG-fMRI
Vadim Zotev1, Han Yuan1, Raquel Phillips1, and Jerzy Bodurka1
1Laureate Institute for Brain Research, Tulsa, OK, United States

EEG performed simultaneously with fMRI with millisecond temporal resolution is particularly sensitive to rapid head rotations. Motion artifacts in EEG-fMRI recordings contain useful real-time information about such rotations. We describe a novel and simple approach for deriving additional fMRI motion regressors directly from EEG motion artifacts, and demonstrate its efficiency for patients with major depression. We show that inclusion of four EEG based motion regressors to the GLM model in addition to six fMRI motion parameters reduces average standard deviation of the GLM fit error by 5-10%, especially in frontal and occipital regions. Possible applications of this approach are discussed.

2848.   53 Removal of ballistocardiographic artifacts from EEG recorded inside the MR scanner using an optical motion-tracking system
Pierre LeVan1, Julian Maclaren1, Michael Herbst1, and Jürgen Hennig1
1Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany

This study investigates the use of accurate motion-tracking to remove ballistocardiographic (BCG) artifacts in EEG recorded inside the MR scanner. These artifacts, due to heartbeat-related head motion in the magnetic field, are usually corrected by an averaged artifact subtraction (AAS) method, which consists of subtracting a template formed by averaging EEG signals from each cardiac cycle. However, AAS cannot model artifact variability across cardiac cycles, preventing a complete removal of BCG artifacts. Motion measurements during scanning were used to regress out residual BCG waveforms, resulting in significantly reduced root-mean-square residuals across cardiac cycles and improved EEG quality.

2849.   54 Correction for T1 effect incorporating flip angle estimated by Kalman filter in cardiac-gated fMRI
Jaemin Shin1, and Xiaoping Hu1
1Biomedical Engineering, Georgia Tech/Emory University, Atlanta, GA, United States

To overcome cardiac pulsation related artifact, cardiac-gated acquisition has been utilized with correction for T1 effect due to variation of the cardiac cycle but it is only valid for the flip angle of 90°. B1 inhomogeneity can often cause a significant variation in flip angle, e.g., 65° to 105° over the brain volume for a nominal flip angle of 90° at 3 T. In this work, we developed a generalized correction technique for T1 effect incorporating actual flip angle, estimated from fMRI dataset itself using Unscented Kalman filter. The new technique is demonstrated with simulated data and in vivo data.

2850.   55 Removal of synergistic physiological motion and image artefacts in functional MRI of the human spinal cord
Patrick W Stroman1, Rachael L Bosma1, Michaela Beynon1, and Christine Dobek1
1Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada

An improvement in physiological noise removal in spinal cord fMRI data is demonstrated. A combination of phase errors due to flow of cerebrospinal fluid (CSF), and image artefacts at high intensity boundaries between CSF and adjacent tissues, is revealed by means of computer simulations of the spinal fMRI acquisition. Spatially and temporally variant signals are demonstrated that do not match the timing of the CSF flow itself. However, the cause of this physiological noise enables it to be modeled as a convolution of a distortion operator, and the unaffected data, and we demonstrate a means of modeling and removing it.

2851.   56 Regressor Selection for RETROICOR and RETROKCOR Corrections of 3D FMRI Data
Rob H.N. Tijssen1,2, Mark Jenkinson1, and Karla L. Miller1
1FMRIB Centre, Oxford University, Oxford, United Kingdom, 2University Medical Center Utrecht, Utrecht, Netherlands

In this work we explore the use of retrospective corrections, in order to remove temporal instabilities from 3D FMRI acquisitions. Using the Bayesian Information Criterion (BIC) to determine an optimal subset, previously proposed for RETROICOR, we aim to optimize the regressor set for various 3D acquisition methods (e.g., SPGR and bSSFP). The results suggest that the optimal number of regressors is highly dependent on the acquisition and can even be zero (i.e., no retrospective correction) in some cases (e.g., when a real-time cardiac synchronized readout is used to correct for cardiac fluctuations prospectively).

2852.   57 Cost-effective fMRI normalization improves differentiation between subject categories: the first clinical demonstration
Peiying Liu1, Carolyn Sacco2, Yan Fang2, Carol Tamminga2, and Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 2Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States

The power of fMRI in assessing neural activity and detecting group differences are often hampered by variations in fMRI responses across individuals. Normalization of fMRI signals with basal physiologic parameters may be useful in reducing variations and improving sensitivity, but this utility hasn’t been tested in patient populations. The present work extends previous findings in healthy controls, and showed a modulation effect of baseline venous oxygenation on fMRI signals in Schizophrenia patients. The results demonstrated that, by accounting for basal physiologic parameters, the sensitivity of fMRI in differentiating patient population from healthy controls can be enhanced with relatively little cost.

2853.   58 A real-time fMRI communication interface for Turbo-BrainVoyager 3.0 using the TBV 3.0 Plugin Interface
Michael Lührs1, Charles Müller1, and Johannes Bernarding1
1Department of Biometry and Medical Informatics, Otto von Guericke University Magdeburg, Magdeburg, Saxony-Anhalt, Germany

Real-time fMRI communication interface between Turbo-BrainVoyager 3.0 and other software tools, providing transfer of multiple data (ROI's) and datatypes based on the TCP/IP protocol.

2854.   59 Single trial classification of complex hand movements using high field fMRI
M.G. Bleichner1, J. M. Jansma1, M. Raemakers1, J. Sellmeijer1, E.J. Aarnoutse1, J.C.W. Siero2, N. Petridou2, and N.F. Ramsey1
1Dept. of Neurology and Neurosurgery, University Medical Center Utrecht, Rudolf Magnus Institute of Neuroscience, Utrecht, Netherlands, 2Dept. of Radiology, University Medical Center Utrecht, Rudolf Magnus Institute of Neuroscience, Utrecht, Netherlands

Decoding the neuronal activity of complex hand gestures, as used in sign languages, could be an interesting way to control a brain computer interface. Thinking about hand gestures representing letters could be translated directly into text on a computer screen. Here we study the underlying neuro-physiological changes of executed hand movements using high field fMRI. We show that single trial classification is possible and that different hand gestures can be distinguished based on the underlying neuronal activation pattern. We conclude that complex hand gestures are a promising control signal for brain computer interfaces.

2855.   60 Composite Hypothesis Testing via Support Vector Regression
Nagesh Adluru1, Richard J. Davidson1, and Andrew L. Alexander1
1University of Wisconsin-Madison, Madison, WI, United States

Hypothesis testing is one of the most commonly performed statistical analyses in neuroimaging studies. Often the goal is to study the effects of variables such as physiological, behavioral and/or clinical on a variety of neuroimaging measurements e.g., cortical thickness, bold-activation, microstructural properties. A most common approach to test the significance of these effects is to project the measured neuroimaging data onto the linear models defined using the variables of interest via ordinary least squares. In this paper we propose that using a more robust projection can increase sensitivity to the effects and hence can also control for confounding parameters.

2856.   61 Enhancement of Temporal Resolution and BOLD Sensitivity in Real-Time fMRI using Multi-Slab Echo-Volumar Imaging
Stefan Posse1,2, and Elena Ackley1
1Neurology, University of New Mexico, Albuquerque, NM, United States, 2Electrical and Computer Engineering, Physics and Astronomy, University of New Mexico, Albuquerque, NM, United States

Real-time fMRI using multi-slab echo volumar imaging was performed with temporal resolution of 286 ms for whole brain acquisition and 136 ms for partial brain acquisition on a clinical 3 Tesla MRI scanner equipped with 12-channel head coil. Whole brain EVI with 286 ms temporal resolution of visual and motor tasks significantly increased average and maximum percent BOLD signal change, average and maximum t-score, and extent of activation compared with EPI. Partial brain EVI with 136 ms temporal resolution exhibited comparable percent signal change, enabled nonaliased detection of heartbeat correlated signal fluctuation and improved sampling of the hemodynamic response function.

62 Multiplexed spiral sequence for high temporal resolution resting state fMRI
Benedikt Andreas Poser1, and V Andrew Stenger1
1UH-QMC Neuroscience and MR Research Program, University of Hawaii, Honolulu, Hawaii, United States

There is demand for shorter whole-brain fMRI acquisition times to allow clear separation of signals from resting state networks and unwanted phsysiological fluctuations (e.g. motion, respiratory and cardiac noise). “Multiplexed” 2D EPI has been proposed to improve temporal resolution. We investigate multiplexed spiral-in acquisition as a more efficent approach because TE is at the end of the sequence. Factor three multiplexing gave whole brain coverage with 36 slices in 420ms. RS fMRI at 3T showed clear sampling of physiologcial noise in the time courses.

2858.   63 Increased temporal resolution in fMRI using Hadamard-encoding with phase correction and physiological noise removal
Alan Chu1, Jon-Fredrik Nielsen1, and Douglas C. Noll1
1Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States

Hadamard-encoded fMRI is a multi-slice acquisition method that potentially increases temporal resolution compared to conventional, single-slice fMRI. Because Hadamard-encoded fMRI is relatively more susceptible to signal variations from both physiological and non-physiological sources, it is critical to perform appropriate noise removal for the method to perform well. In this abstract, we outline the proper processing needed for Hadamard-encoded fMRI, and show that the results have increased temporal resolution without a decrease in activation quality.

2859.   64 High temporal resolution fMRI-study of trial-by-trial brain function in Visual attention
Mehdi Ordikhani-Seyedlar1, Benjamin Zahneisen1, Thimo Hugger1, Jürgen Hennig1, and Pierre LeVan1
1Radiology and Medical Physics, University-Medical Center Freiburg, Freiburg, Germany

Our aim was to use a new technique to acquire the whole brain functional imaging data at a high temporal resolution of 100ms while doing a visuospatial attention task. This study showed that high temporal resolution fMRI can successfully measure small fluctuations in trial-by-trial BOLD signal correlated with reaction time in order to identify the emergence of functional networks in the brain during the execution of a cognitive task.

2860.   65 Comparison of Simultaneous Multiband Whole Brain Imaging with Multiplexed-EPI
Liyong Chen1,2, Audrey Chang1,2, Junqian Xu3, Steen Moeller3, Edward J Auerbach3, An Thanh Vu1,2, Kamil Ugurbil3, Essa Yacoub3, and David Feinberg1,2
1Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States, 2Advanced MRI Technologies, Sebastopol, CA, United States,3Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minneapolis, MN, United States

Multiplexed-EPI is performed using different number of images readout simultaneous in the EPI echo trains. Compared in whole brain imaging, slice accelerations (M) of 6 to 48 images per echo train were evaluated. Results showed observable trade-offs in image quality at highest accelerations using single echo trains to scan the whole brain and good quality images using two or three echo trains.

2861.   66 Investigating the performance of ZOOM-EPI for fMRI in the brain
Moreno Pasin1, Marios C Yiannakas1, Ahmed Toosy2, and Claudia A M Wheeler-Kingshott1
1NMR Research Unit, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, England, United Kingdom, 2NMR Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, United Kingdom

In this study we assess the performance of the ZOnally-magnified Oblique Multislice EPI (ZOOM-EPI) sequence using a reduced field of view for targeted areas of fMRI activation. We compared motor fMRI activations on 5 healthy subjects obtained using ZOOM-EPI with ones obtained using conventional GE-EPI and SE-EPI sequences in terms of their spatial localisation. Moreover we report the dimensions of the activated regions in each subject for the three different sequences. For all subjects the ZOOM-EPI showed good anatomical correspondence with the overlapping activated areas from the more conventional GE-EPI and SE-EPI sequences and more localised activation.

2862.   67 Submillimeter fMRI at 3T using Long Axis PROPELLER-EPI
Martin Krämer1, and Jürgen R Reichenbach1
1Medical Physics Group, Department of Diagnostic and Interventional Radiology I, Jena University Hospital, Jena, Germany

Using the PROPELLER-EPI technique for functional magnetic resonance imaging has the advantage that, albeit the multi-shot nature of the method, acceptable temporal resolutions can be achieved. At the same time the readout train length is significantly reduced, enabling high in-plane resolutions. In our work we demonstrate that long-axis PROPELLER-EPI can be used for performing fMRI with submillimeter resolution at a clinical field strength of 3T. Results from a finger tapping experiment are presented with an in-plane resolution of 0.7 mm2

2863.   68 High-resolution fMRI experiments on visual cortex using consecutive interleaved EPI at 7T
Dae-Hun Kang1, Uk-Su Choi1, Jun-Young Chung1, Da-Eun Kim1, Young-Bo Kim1, and Zang-Hee Cho1
1Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea

Using consecutive interleaved multi-shot EPI scheme (ciEPI) with minimal intersegment delay and parallel imaging is one of methods to obtain less-distorted images. Recently, multiple stimulus-driven retinotopic maps were introduced using conventional EPI schemes in the previous study. In a present paper, a retinotopic response is observed by visual stimuli through ciEPI schemes with high-resolution at 7T.

2864.   69 High temporal resolution and physiological noise removal improve BOLD detection in brainstem and auditory cortex at 7T
Wietske van der Zwaag1,2, Mayur Narsude1, João Jorge3, José Pedro Marques1,2, and Rolf Gruetter1,2
1Université de Lausanne, Lausanne, VD, Switzerland, 2LIFMET, EPFL, Lausanne, VD, Switzerland, 3Instituto Superior Técnico, Lisbonne, Switzerland

Physiological noise can prohibit the detection of BOLD signal variations. The movement of the brainstem during the cardiac cycle amplifies this problem locally. In this study, the effect of (1) temporal resolution of a 3D-EPI acquisition and (2) physiological noise removal on BOLD detection in primary auditory cortex AI and the brainstem were investigated. Physiological noise removal was essential for BOLD signal detection in the brainstem at the axial slice orientation used. In addition, higher temporal resolution increased the number of active voxels significantly. Increases in BOLD sensitivity with shorter TR and physiological noise removal were also found in AI.

2865.   70 High-resolution sparse-sampling fMRI reveals tonotopic organization of human inferior colliculus
David Ress1, Reswanul Khan2, Bharath Chandresekaran3, and Seth Koslov3
1Neurobiology, Psychology, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States,2Neurobiology, Physics, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States,3Communication Sciences and Disorders, The University of Texas at Austin, Austin, TX, United States

We present a high-resolution sparse-sampling fMRI approach for imaging small auditory brainstem structures. High resolution is obtained with a multi-shot spiral acquisition. Sparse sampling is obtained by two adjustments to the fMRI pulse sequence. First, quiet periods are created by disabling the acquisition gradients for long periods (9 s) to permit delivery of auditory stimuli. Second T1-equilibrium is maintained by continual delivery of slice-selective excitation pulses throughout each scanning run. Using this approach, we have obtained 1.2-mm sampling in human inferior colliculus (IC) with satisfactory contrast-to-noise ratio. The data confirm a laminar organization of stimulus frequency representation in human IC.

2866.   71 Depth characterization of the BOLD hemodynamic response function in human early visual cortex
Reswanul Khan1, Sucharit Katyal2, Clint Greene2, Evan Luther3, and David Ress2
1Neurobiology, Physics, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States,2Neurobiology, Psychology, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States,3Neurobiology, Biomedical Engineering, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States

At conventional resolutions, BOLD fMRI samples responses from various tissues in cerebral cortex: white matter, gray matter, and extra-pial. Here, we utilize high-resolution fMRI (0.9-mm voxels) to characterize the BOLD hemodynamic response function (HRF), as it varies with depth and tissue type in cortex. Surface-based analysis methods create a normalized depth coordinate that permits characterization throughout the variable thickness of gray matter. The HRF peak response occurs faster in deep gray matter, but is stronger and noisier in more superficial tissue. No significant initial dip is present in the gray matter, but is clearly evident in extra-pial tissues.

2867.   72 Columnar organization or noise? Optimization and validation of fMRI at the resolution of columns
Denis Chaimow1,2, Kamil Ugurbil1, and Amir Shmuel1,3
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 2Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 3Montreal Neurological Institute, McGill University, Montreal, QC, Canada

The ability of high-field fMRI to truly resolve columnar organization depends on the spatial scale of the pattern, the BOLD point spread, the voxel size and the noise level. To better understand the role of each factor, and to guide the selection of optimal parameters, we developed a mathematical model of imaging cortical columns. We quantified the expected differential functional contrast relative to noise and the expected similarity between the imaged pattern and the true columnar organization as a function of parameters of interest. We found that the voxel width that optimizes differential contrast is larger than the one that optimizes accuracy. Furthermore, we propose a method for confirming that an imaged pattern reflects the true columnar organization.
Electronic Poster Session - fMRI

fMRI: Connectivity Analysis & Novel Contrasts
Click on to view the abstract pdf and click on to view the video presentation. (Not all presentations are available.)
Monday 7 May 2012
Exhibition Hall  10:45 - 11:45

  Computer #  
2868.   73 Reduced Local BOLD Correlation in Pre-Frontal Cortex during Deep Sleep
Xiao Liu1, Silvina G. Horovitz1,2, Allen R. Braun3, Walter S. Carr4, Dante Picchionie5, Masaki Fukunaga1, and Jeff H. Duyn1
1Advanced MRI section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States, 2Human Motor Control Section, MNB, National Institutes of Health, 3Language Section, Voice, Speech and Language Branch, NIDCD, National Institutes of Health, 4Naval Medical Research Center, 5Department of Behavioral Biology, Walter Reed Army Institute of Research

In this study, the average temporal correlation of spontaneous BOLD fMRI activity within local brain regions was computed and compared between the wake and slow wave sleep (SWS) stages in human. Significant reductions in local BOLD correlation were primarily found in the prefrontal cortex during the SWS, while increases were limited to posterior brain regions. The finding is consistent with the notion that prefontal activity is an important constituent of higher cognitive function during conscious awareness, and the fact that the latter is reduced during SWS. This suggests that the distribution of local correlation may report on cognitive state.

2869.   74 Disturbed Coherence of Information Processes as Revealed by Intrinsic Functional Connectivity during Propofol Anesthesia
Maolin Qiu1, Ramachandran Ramani2, and R. Todd Constable1,3
1Diagnostic Radiology, Yale University, New Haven, CT, United States, 2Anesthesiology, Yale University, New Haven, CT, United States, 3Biomedical Engineering, and Neurosurgery, Yale University

Process-coherence theories have been proposed by anesthesiologists about anesthesia and unconsciousness and they were originally based on clinical observations of neuronal activity in sleep, epileptic, or vegetative patients. It has been difficult to test hypotheses involving disruptions in the coherence of neural activity until very recently with the development of techniques for reliably assessing intrinsic functional connectivity contrast (ICC). We used ICC power to quantify changes in communications between neural networks, upon administration of Propofol, and test the hypothesis of process-coherence theories. Our results demonstrate the enhancement of synchronous oscillations in the DMN in the presence of Propofol, and such increases in synchronous oscillations may be a prerequisite for producing sleepiness and unconsciousness.

2870.   75 Mapping of cortico-cortical and cortico-subcortical alterations in functional connectivity induced by light sedation with propofol.
Tommaso Gili1, Neeraj Saxena2, Ana Diukova1, Kevin Murphy1, Judith E Hall2, and Richard G Wise1
1Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff, United Kingdom, 2Section of Anaesthetics, Intensive Care and Pain Medicine, Cardiff University School of Medicine, Cardiff, United Kingdom

We have examined alterations in functional connectivity induced by propofol sedation in a group of healthy volunteers. Large cortical areas (occipital, temporal, frontal and parietal) were used as seed regions for the functional connectivity analysis. While there appeared to be little involvement of the default-mode network in sedation related changes, thalamo-cortical functional connectivity was modified. This is consistent with previous suggestions of altered thalamo-cortical communication in sedation and pharmacologically induced loss of consciousness.

2871.   76 Can time under anesthesia affect resting state connectivity?
Benito de Celis Alonso1, Silke Kreitz2, Silvia Hidalgo Tobón3, Carlos Herrera1, Florian Spiegel2, Sebastian Spiegel2, Marina Sergeyeva2, and Andreas Hess2
1Faculty of Medicine, BUAP, Benemérita Universidad Autónoma de Puebla, Puebla, PUE, Mexico, 2Pharmacology and Toxicology, FAU Erlagen-Nuremberg, Erlangen, Bayern, Germany, 3UAM Universidad Autónoma de México, Mexico

Resting-state imaging analyzes the low frequency fluctuations of the BOLD signal (0.01-0.1 Hz) when brain is at rest. It is accepted that these fluctuations reflect neuronal activity (1,2) and also a certain degree of structural (3) and functional connectivity (4). It is known that resting states are reproducible in other order of mammalians (5) and that they are not affected by sleep (6) or even sedation (7). Results for rodents are obtained regularly under anesthesia and apparently the narcotic has no effect on resting-states (8,9) even if other authors establish that there should be anesthetic confounds (10, 11). No study tackles the effect on resting-states of total experimental time under anesthesia. In this study, we compared resting states in two scenarios, one before and after an fMRI experiment and other when no fMRI experiment was performed between resting state measurements. Our results show that there is a decay in both cases of correlation strength that depends on the total time animals have been under anesthesia, This decay does not seem to imply a change in the nature of the correlations.

2872.   77 Disruption of interhemispheric functional connectivity by peripheral nerve block
Todd B Harshbarger1, M. Stephen Melton2, Allen W Song1, and Stephen Klein2
1Brain Imaging and Analysis Center, Duke University, Durham, NC, United States, 2Anesthesiology, Duke University Medical Center, Durham, NC, United States

Functional connectivity is increasingly used to compare normal brain states with various disorders. In this study, we investigated resting state functional connectivity before and after a peripheral nerve block. We show that cross-hemispheric correlations in motor areas which exist before the block is applied are disrupted by the nerve block. These correlations return immediately after the block wears off. This can have implications in the study of connectivity and correlations between hemispheres, as well as potential implications for studies of how the brain reacts to damage in the peripheral nervous system.

2873.   78 Impaired Functional Connectivity between the Hippocampus and Dorsolateral Prefrontal Cortex in a Neonatal Hippocampal Lesion Macaque Model
Chunxia Li1, Zhihao Li2, Xiaoping Hu2, Jocelyne Bachevalier3, and Xiaodong Zhang1,4
1Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, United States, 2Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States, 3Yerkes National Primate Research Center and Department of Psychology, Emory University, Atlanta, Georgia, United States, 4Division of Neuropharmacology and Neurologic Disease, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, United States

Macaques with neonatal hippocampal lesions showed hippocampal-dependent and prefrontal-dependent memory deficits similar to those reported in schizophrenic patients and are thus an ideal animal model to study the mechanism of the abnormal functional connectivity reported in schizophrenia. In this study, rhesus monkeys with neonatal hippocampal lesions were used to investigate the functional connectivity between the hippocampus (HP) and the dorsolateral prefrontal cortex (DLPFC) with the resting-state functional MRI technique. The results showed weaker functional connectivity between left HP and left DLPFC in animals with neonatal HP lesions, and the degree of abnormal connectivity was significantly correlated with volume of HP lesion.

79 Resting-state Functional Connectivity Altered by Complete and Partial Corpus Callosotomy in Rats
Iris Y. Zhou1,2, Y. X. Liang3, Joe S. Cheng1,2, Russell W. Chan1,2, Kevin C. Chan1,4, K. F. So3, and Ed X. Wu1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China, 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China, 3Department of Anatomy, The University of Hong Kong, Hong Kong SAR, China, 4Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, United States

Resting-state fMRI has been increasingly used in the diagnosis of a variety of brain diseases. However, the underlying mechanism of the spontaneous fluctuations in rsfMRI signals is still under debate. In this study, the effects of complete and partial transection of corpus callosum (CC) on rsfMRI signal were investigated. The loss of interhemispheric functional connections after the complete transection of CC was observed. More importantly, partial CC transection disrupted only the specific intercortical functional connection that is known to be anatomically connected through CC. These findings further indicate that the spontaneous fluctuations in rsfMRI signal largely reflect the anatomical connections.

2875.   80 Changes in Resting Connectivity between Functional Networks in a Patient with Significant Recovery from Complete Cervical Spinal Cord Injury
Ann S Choe1,2, Visar Belegu1,2, Cristina Sadowsky2,3, Peter C van Zijl4,5, James Pekar4,5, and John McDonald1,2
1Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2International Center for Spinal Cord Injury, Hugo Moser Research Institute at Kennedy Krieger Inc, Baltimore, MD, United States, 3Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 4Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 5F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States

Can MRI inform classification of spinal cord injury (SCI), and assess consequent brain changes? In this study, we used advanced MR methods to report on the structural and functional alterations in the central nervous system of a patient who recovered significant neurological function after SCI. Pattern of changes in diffusion tensor imaging and magnetization transfer imaing-derived parameters in the cord was consistent with the subject¡¯s motor and sensory function evaluations, and the changes in the BNC of the subject was consistent with the subject¡¯s clinical presentation, suggesting that rs-fMRI can be used to observe brain functional changes of SCI subjects.

2876.   81 Structural and functional connectivity in amyotrophic lateral sclerosis
Molly Claire Chapman1, Laura Marie Jelsone-Swain2, and Robert Cary Welsh2
1School of Medicine, University of Michigan, Ann Arbor, MI, United States, 2Radiology, University of Michigan, Ann Arbor, MI, United States

We examine diffusion tensor metrics and resting state functional connectivity in an amyotrophic lateral sclerosis population.

2877.   82 Abnormality of variance of resting state fMRI signal in white matter for schizophrenia
Hu Cheng1, Jerillyn Kent1, Mallory Klaunig1, Dae-Jin Kim1, Brian O'donnell1, William Hetrick1, and Aina Puce1
1Indiana University, Bloomington, IN, United States

Recently, abnormalities in the amplitude of low frequency resting state fMRI signal have been observed in schizophrenia patients. In this report, we examined the variance of the signal in resting state fMRI across the whole brain, and found significant differences between schizophrenia patients and non-patient controls. The controls showed higher temporal SNR mainly in the white matter, clustered in several regions including temporal, frontal, and parietal lobes, cerebellum, anterior cingulate, and major white matter tracts. White matter abnormalities in these regions have been previously reported in schizophrenia patients.

2878.   83 Complexity and synchronicity of resting state fMRI in normal aging and familial Alzheimer's disease
Collin Liu1,2, Anitha Priya Krishnan3, Lirong Yan1, Jeffrey R Alger1, John Ringman4, and Danny JJ Wang1,4
1Ahmanson-Lovelace Brain Mapping Center, UCLA, Los Angeles, CA, United States, 2Neurobehavior Unit, VA Greater LA Healthcare System, Los Angeles, CA, United States, 3Molecular Imaging Center, USC, Los Angeles, CA, 4Neurology, UCLA, Los Angeles, CA

Interpretation of biological signals is essential for diagnosing diseases. Pattern recognition and spectral analyses have commonly been used. More recently a non-linear time-series analysis called approximate entropy has been applied to EEG, ECG, and hormonal levels. Here we applied approximate entropy to resting state BOLD fMRI time-series, to characterize the complexity of the signal in normal aging and familial Alzheimer's disease. Similar calculation can be made between the time-series of a seed voxel and that of all other voxels to provide a measure of synchronicity. This is called cross-approximate entropy. These analyses might provide novel measures of functional connectivity, complementary to cross-correlation.

2879.   84 The power spectral density of slow fluctuation BOLD signal analysis during resting-state functional magnetic resonance image in fibromyalgia
Jeehye Seo1, Hui-jin Song1, Seong-Uk Jin1, Hee-Kyung Kim1, Jang Woo Park1, Moon Han1, Jong Su Baeck1, Ji-Young Kim2, and Yongmin Chang1,3
1Medical & Biological Engineering, Kyungpook National University, Daegu, Jung-gu, Korea, 2School of Medicine, Kyungpook National University, Daegu, Jung-gu, Korea, 3Molecular Medicine, Kyungpook National University, Daegu, Jung-gu, Korea

Fibromyalgia (FM) is a medical disorder characterized by chronic widespread pain, a heightened and painful response to pressure. Currently, no investigation is available for identifying the power spectral density of low frequency BOLD fluctuations during resting-state functional magnetic resonance imaging (rs-fMRI) while recent study evaluated functional connectivity of low frequency fluctuation in FM patients. Using seed-based analysis of low frequency BOLD fluctuations in pain related networks, our results demonstrated (1) the medial and lateral pain networks of slow fluctuation BOLD signal during rs-fMRI and (2) the differences in the power spectral density within pain-related networks between FM patients and healthy controls.

2880.   85 Spatiotemporal Correlation of Optical Neuronal Calcium Recordings with BOLD fMRI in Rats
Albrecht Stroh1, Florian Schmid2, Lydia Wachsmuth2, Valentin Riedl1, Afra Wohlschlaeger3, Jenny Kressel3, Claus Zimmer3, and Cornelius Faber2
1Technical University Munich, Munich, Germany, 2University Hospital Muenster, Germany, 3Technical University Munich, Germany

Furthering our understanding of the spatiotemporal dynamics of neurovascular coupling requires the simultaneous and unperturbed recording of neuronal spiking and BOLD fMRI. Here, we demonstrate the feasibility of optical recording of neuronal activity with sub-millisecond temporal precision within a 9.4 T small animal scanner and simultaneously recording BOLD fMRI. Using fluorescent indicators for intracellular Ca2+ concentrations, we achieve a direct optical readout of super-threshold neuronal spiking activity, enabling the temporal and spatial correlation of BOLD time course and neuronal firing patterns.

2881.   86 The Influence of Laser Power and Pulse Characteristics on the Optogenetically Induced BOLD Signal of Excitatory Neurons in the Mouse Hippocampus at 9.4T
Philipp Lebhardt1, Wolfgang Kelsch2,3, Claudia Falfan-Melgoza1, Gabriele Ende1, Alexander Sartorius2, and Wolfgang Weber-Fahr1
1NeuroImaging, Central Institute of Mental Health, Mannheim, Germany, 2Clinic of Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany, 3Cinical Neurobiology, University of Heidelberg, Hiedelberg, Germany

In this study we were interested in the influence of laser power and stimulation frequency on the optogenetically induced BOLD signal of the hippocampal network in mice. We induced expression of channelrhodopsin-2 in Ca2+/calmodulin-dependent protein kinase II-expressing neurons by virus injection. Laser stimulation was periodically applied through an optical fiber in the left hippocampus with block and event related designs using different power and stimulation characteristics. We found activation and deactivation due to laser heating effects even at low power levels and diverse activation patterns in dependency of stimulation length and frequency

2882.   87 Optogenetic control of the BOLD response during local suppression of neuronal activity by muscimol
Daniil Aksenov1,2, Limin Li1,2, Michael Miller1,2, George Iordanescu1,2, and Alice Wyrwicz1,2
1NorthShore Univ. RI, Center for Basic MR Research, Evanston, IL, United States, 2Pritzker Sch. of Med., Univ. of Chicago, Chicago, IL, United States

Optogenetic control offers great potential for studying the relationship between BOLD and neuronal activity in specific cell populations under a variety of modulatory conditions. In this work, we combine simultaneous fMRI and electrophysiological recording in the whisker barrel cortex with localized pharmacological modulation and optogenetic stimulation to examine the BOLD response in awake rabbits before and after local injection of the GABA-A agonist muscimol. Our results indicate that BOLD area and magnitude are preserved during optical stimulation in the cortex even in the presence of increased inhibition produced by muscimol injection, but thalamic BOLD response decreased after injection.

2883.   88 Arterial cerebral blood volume (CBVa) weighted functional MRI using pseudocontinuous arterial spin labeling
Hesamoddin Jahanian1,2, Scott Peltier1,2, Douglas C Noll1,2, and Luis Hernandez-Garcia1,2
1Functional MRI Laboratory, University of Michigan, Ann Arbor, Michigan, United States, 2Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States

Functional magnetic resonance imaging using physiological parameters such as cerebral blood perfusion or cerebral blood volume (CBV), unlike BOLD fMRI, provides a quantifiable contrast and is also more closely related to neural activity. Current Perfusion-based fMRI techniques, however, suffer from poor sensitivity and low temporal resolution. It has recently been shown that the change in CBV during neural activation mainly originates from arterial rather than venous blood volume, but CBV-based fMRI methods (such as VASO and MOTIVE) are also limited by their low signal to noise ratio. We propose a novel method based on pseudocontinuous arterial spin labeling (pCASL) technique to achieve a contrast that depends on arterial cerebral blood volume (CBVa) and can be used for functional imaging experiments. The method proposed here offers sensitivity to brain activation that is on par with BOLD imaging and superior to perfusion ASL, while maintaining most of the advantages of perfusion ASL imaging.

2884.   89 Functional Blood Volume Imaging (fBVI) using Blood Pool Gadolinium Contrast Agent Gadofosveset Trisodium
Deqiang Qiu1, David E Rex1, Manojkumar Saranathan1, Robert M Lober2, Greg Zaharchuk1, Michael E Moseley1, and Kristen W Yeom1
1Radiology, Stanford University, Stanford, CA, United States, 2Neurosurgery and Division of Child Neurology, Stanford University, Stanford, CA, United States

Functional MRI (fMRI) has commonly been performed using a T2*-based BOLD (Blood oxygenation level dependent) technique, which depends on complex interactions between multiple physiological processes and has inherent resolution limits due to sensitivity to large veins. In this paper, we present the first human demonstration of the use of blood pool agent gadofosveset trisodium (Ablavar) for functional T1-based blood volume MRI. Development of T1 contrast agent based fMRI will lead to high-resolution and distortion-free brain mapping techniques.

2885.   90 Evaluation of a functional MRI Assay Using a Novel USPIO Contrast Agent (Ferumoxytol) in Normal Healthy Volunteers
Richard Baumgartner1, William Cho2, Alexandre Coimbra2, Cynthia Gargano3, Robert Iannone4, Arie Struyk4, Rebecca Fox4, Zaiqi Wang4, Fuqiang Zhao5, Donald Williams5, Torsten Reese6, Brian Henry7, Esben Petersen8, Chris Chen9, Dai Feng3, Sofia Apreleva3, and Jeffrey Evelhoch5
1Biostatistics and Research Decision Sciences (BARDS), Merck Research Laboratories (MRL), Rahway, New Jersey, United States, 2Genentech, 3BARDS, MRL, 4Experimental Medicine, MRL, 5Imaging, MRL, 6Center for Cooperative Research in Biomaterials, Spain, 7Translational Medicine Research Center, MRL,8Clinical Imaging Center, Singapore, 9Singapore National University


91 An fMRI Phantom Based on the Alignment of Molecular Dipoles with an Electric Field
Yujie Qiu1, Edmund Kwok2, and Joseph P Hornak1
1Imaging Science, Rochester Institute of Technology, Rochester, NY, United States, 2Imaging Science, University of Rochester Medical Center, Rochester, NY, United States

A new concept for an fMRI phantom is presented where the T2 of a non-viscous, high dielectric constant liquid is changed by the application of an electric field. The electric field aligns the dipoles in the liquid, thus changing the molecular motions and T2. The T2 value of propylene carbonate was changed from 45 to 36 ms by the application of a 116 V/cm electric field. This T2 change will produce a 15% change in the signal, comparable to the 5-20% seen for the BOLD response. This concept may allow changing the T2 at rates comparable to the BOLD response.

2887.   92 MRI detection of short-duration "epileptiform" discharges in an ionic-current phantom
Mukund Balasubramanian1, Padma Sundaram1, William W. Wells2, Tobias Loddenkemper3, Robert V. Mulkern1, and Darren B. Orbach1
1Department of Radiology, Children's Hospital Boston, Boston, Massachusetts, United States, 2Department of Radiology, Brigham and Women's Hospital,3Department of Neurology, Children's Hospital Boston, Boston, Massachusetts, United States

In order to determine the limits of detecting short-duration currents with the phase of gradient-echo EPI, we imaged a phantom carrying ionic currents of various amplitudes and duty cycles, including those approximating epileptiform activity. Our results demonstrate the feasibility of detecting DC pulses with durations of 200 milliseconds or longer, for current amplitudes that are plausible for interictal discharges. Although our particular focus is on epilepsy, the ability to reliably image neuronal currents in general would provide a novel and important contrast mechanism for fMRI, with widespread applicability.

2888.   93 Combined Vessel Size and Blood Flow Imaging with Hyperoxia
Michael Germuska1, Thies Jochimsen2, Michael Kelly1, Tom Okell1, and Daniel Bulte1
1Nuffield Dept. of Clinical Neurosciences, University of Oxford, Oxford, Oxon, United Kingdom, 2PET-MR Group, Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany

Of particular interest when assessing neuro-angiogenesis are changes in blood flow, blood volume and vessel size. Here we present an MR imaging protocol that maybe used to make simultaneous measurements of these parameters in humans. The protocol uses a modified pseudo-continuous ASL sequence, with a dual gradient-spin echo EPI readout. Periods of mild hyperoxia are used to modulate the BOLD signal during acquisition. Mean vessel size maps and blood volume are calculated from the change in spin echo and gradient echo images. While the gradient echo signal is used to calculate resting blood flow.

2889.   94 Comparisons of diffusion-weighted and BOLD fMRI signals in the rat somatosensory cortex.
Tomokazu Tsurugizawa1, Luisa Ciobanu1, and Denis Le Bihan1
1Neurospin, Gif sur Yvette, France

Diffusion-weighted functional MRI (DfMRI) has been shown to be sensitive to neural activation in the human brain. In this study, I compared the DfMRI (b=10, 250, and 1800) and BOLD signal changes in rat somatosensory cortex under hyperoxia without neuronal stimulation and forepaw electrical stimulation. The amplitude of the high b-value DfMRI (b=1800) signal was lower than those of BOLD signal during hyperoxia. During the forepaw stimulation, early return-to-baseline of the high b-value DfMRI response was observed compared to BOLD response. These results show that the BOLD and DfMRI signal point out different mechanisms.

2890.   95 Activation by fasting changes diffusion parameters of the hypothalamus in the adult human brain as detected by DWI
Blanca Lizarbe1, Maria Lusia Garcia-Martin2,3, Pilar Lopez-Larrubia1, and Sebastian Cerdan1
1Instituto Investigaciones Biomedicas "Alberto Sols", Madrid, Spain, 2Magnetic Ressonance Unit, Clinica Nuestra Senora del Rosario, Madrid, Spain, 3Head Nano-Imaging Facility, Parque Tecnológico de Andalucía, Malaga, Spain

We report on the use of functional DWI as a robust marker of hypothalamic activation by fasting in human subjects. Six adult male where imaged (DWI, three directions) in two different situations, fed (after one week of a balanced diet), and after 24 hours of fasting. Two areas of the brain, the hypothalamus and the cortex, were investigated using a biexponential model of diffusion. Fasting is shown to elicit significant, and directionally-dependent, changes of the biexponential diffusion parameters in the hypothalamus, suggesting an activation-induced cell swelling. These results open the possibility to examine feeding disorders and their therapies by DWI.

2891.   96 Validation of Diffusion-Weighted FMRI signal in vitro using brain slices
Nyoman D. Kurniawan1, John Power2, Natalie Alexopoulos1, Donald J Maillet3, Michael Vogel1, Ian M. Brereton1, and David C. Reutens1
1Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia, 2Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia, 3Centre for Advanced Imaging, University of Queensland, Brisbane, Australia

Diffusion-weighted FMRI (DFMRI) was suggested to provide a more direct measurement of neuronal activation (Le Bihan et al., 2006). DFMRI methods are thought to reflect cell swelling and a reduction in extracellular space accompanying the influx of water and ions in active neurons. However, there is some evidence that in vivo DFMRI signals may be contaminated by haemodynamic/BOLD effects and thus put doubts about the significance and origin of the DFMRI signal. In this study, we aimed to verify the origin of DFMRI signal in vitro using perfused brain slices free from haemodynamic effects. We found that DFMRI could detect activation signal in the absence of hemodynamic effects. In hippocampal slices, K+ stimulation induced changes in DFMRI signal with a similar spatial distribution and time course to that observed with fluorescence microscopy.

Electronic Poster Session - fMRI

fMRI: Neuroscience Applications & Brain Physiology
Click on to view the abstract pdf and click on to view the video presentation. (Not all presentations are available.)
Monday 7 May 2012
Exhibition Hall  11:45 - 12:45

  Computer #  
2892.   73 Activation in thalamus predicts state and trait anxiety: An fMRI perspective of attentional control theory
Shilpi Modi1, Manas K Mandal2, Prabhjot Kaur1, Rajendra P Tripathi1, and Subash Khushu1
1Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi, Delhi, India, 2Defence Institute of Psychological Research, Delhi, Delhi, India

Anxiety impairs the inhibition function and hence, increased distractibility is found in anxious individuals compared with nonanxious ones. fMRI was carried out to map neural correlates for an attention task that required distracter inhibition. Individual differences in state and trait anxiety levels were regressed with individual BOLD activation patterns. Multiple regression analysis results indicate that the activation in thalamus predicted lower state anxiety and higher trait anxiety levels of subjects Results further suggest that different types of anxiety—state or trait—may influence attention differently.

2893.   74 The effect of fat on the cortical response to flavour
Sally Eldeghaidy1,2, Luca Marciani1,3, Tracey Hollowood4, Kay Head1, Johanneke Busch5, Andrew J. Taylor4, Tim Foster6, Robin C. Spiller3, Joanne Hort4, Penny A. Gowland1, and Susan Francis1
1Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom, 2Department of Physics, Suez Canal University, Ismailia, Egypt, 3Nottingham Digestive Diseases Centre NIHR Biomedical Research Unit, Nottingham University Hospitals, Nottinghamshire, United Kingdom, 4Sensory Science Centre, Division of Food Sciences, University of Nottingham, Loughborough, Leicestershire, United Kingdom, 5Unilever R&D, Vlaardingen, Netherlands, 6Division of Food Sciences, University of Nottingham, Loughborough, Leicestershire, United Kingdom

The increase understanding of the impact of fat on the flavour perception could assist the design of food products that are lower in fat but still rewarding to eat. Here, we mapped the cortical representation to no flavoured fat, flavoured no fat, iso-release and perceived flavoured fat emulsions. We show that the presence of fat in the oral cavity reduces the cortical response to flavour, particularly in the primary taste areas and anterior cingulate, even when samples are iso-perceived (or volatile release) for sweetness, flavour and thickness.

2894.   75 Functional MRI of Auditory-Visual Convergence in the Superior Colliculus
Kyle K. Xing1,2, Condon Lau1,2, Patrick P. Gao1,2, and Ed X. Wu1,2
1Laboratory of Biomedical Imaging and Signal Processing, the University of Hong Kong, Hong Kong, China, 2Department of Electrical and Electronic Engineering, the University of Hong Kong, Hong Kong, China

Extensive research has been conducted to understand how the central nervous system receives information from individual sensory channels and converts it into perceptions of sight, sound, touch, smell, and taste. Neurons in the superior colliculus (SC) respond to auditory and visual inputs, but noninvasive fMRI studies have only observed visual responses. In this study, we apply BOLD fMRI on rats to measure the hemodynamic responses in the SC and inferior colliculus following auditory and visual stimulation. Responses are observed in the SC during both stimuli, providing the first fMRI evidence of auditory-visual convergence in the SC.

2895.   76 Group Differences in Brain Activity between Dyslexic Children and Normal Controls Using Functional Magnetic Resonance Imaging
Youngseob Seo1,2, Zhiyue J Wang1,2, Srinivas Rachakonda3, Jonathan M Chia4, and Nancy K Rollins1,2
1Radiology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States, 2Radiology, Children's Medical Center Dallas, Dallas, Texas, United States, 3University of New Mexico, 4Philips Healthcare

Dyslexia is referred to as specific reading disability/retardation in spite of conventional instruction and adequate intelligence. Learning to read is one of the most important skills for children to acquire in early education. We compared brain activities between dyslexic children and normal controls for reading and action-related tasks using fMRI and group ICA. We demonstrated there are differences in brain function activities in visual, executive, auditory, motor, sensory cortexes and Broca’s area between the 2 groups.

2896.   77 Imaging brain response to exercise fatigue and exhaustion: an ASL perfusion study
Ying Hao1, Zhiyue Xia2, Haibin Zhu3, Xiaoying Wang1,3, Jing Fang1,4, Jue Zhang1,4, and Dapeng Bao2
1Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, Beijing, China, 2Beijing Sport University, 3Peking University First Hospital,4Department of Engineering, Peking University

Most studies have utilized noninvasive BOLD-fMRI to depict the central neural adaption to physical fatigue or exhaustion; however, the large-scale effects of exercise on the cardio-pulmonary systems may influence the blood oxygen level dependent (BOLD) signal independent of neuronal activation. Thus, arterial spin labeling (ASL), which is capable of acquiring regional CBF values noninvasively, was proposed here to depict the brain response to exercise fatigue and exhaustion. Eight athletes were conducted the PASL scan pre- and post- the ergometer tasks on fatigue and exhaustion levels. Significant CBF reduction was observed after both kinds of exercises.

2897.   78 The Basal Ganglia Coupling during Social Interaction Revealed by Dyadic fMRI
Ray Lee1
1Neuroscience Institute, Princeton University, Princeton, NJ, United States

Taking advantage of emerging dyadic fMRI (dfMRI), a study on two human-brain interactions inside one MRI scanner was conducted. Besides confirmed most of the previous results regarding BOLD effect in social cognition, the probabilistic independent component analysis (PICA) results of our dfMRI data reveal that the basal ganglia coupling between two brains could be an essential stage in social cognition. This is the first time that fMRI shows that a special region of brain during social interaction becomes correlated, while most other BOLD effects due to social interaction are only coherent within each individual brain.

2898.   79 fMRI Study of Sound Pressure Level Processing in the Central Auditory System
Jevin W. Zhang1,2, Condon Lau1,2, Joe S. Cheng1,2, Kyle K. Xing1,2, Iris Y. Zhou1,2, Matthew M. Cheung1,2, and Ed X. Wu1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China, 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China

Intensity is an important physical property of the sound wave and is usually reported as sound pressure level (SPL). This study examines the fMRI hemodynamic responses in the rat inferior colliculus (IC), lateral lemniscus (LL), medial geniculate body (MGB) and auditory cortex (AC) over a broad 72dB SPL range using sparse temporal sampling. The BOLD signal change increases significantly with SPL in IC and LL, but not in MGB and AC, which agrees with electrophysiology findings. This is the first fMRI observation of differences in SPL dependences between auditory structures and furthers our understanding of SPL processing.

2899.   80 Functional MRI of the Olfactory System in Awake and Anesthetized Dogs
Hao Jia1, Oleg Mykolajovych Pustovyy2, Paul Waggoner3, Ronald J Beyers1, John Schumacher4, Jay Barrett5, Edward Morrison2, Robert L Gillette4, Thomas S Denney1,6, Vitaly J Vodyanoy5, and Gopikrishna Deshpande1,6
1AU MRI research center, Dept. of ECE, Auburn University, Auburn, Alabama, United States, 2Dept. of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama, United States, 3Canine Detection Research Institute, Auburn University, Auburn, Alabama, United States, 4Dept. of Clinical Sciences, Auburn University, Auburn, Alabama, United States, 5College of Veterinary Medicine, Auburn University, Auburn, Alabama, United States, 6Dept. of Psychology, Auburn University, Auburn, Alabama, United States

Canines are used extensively for detecting odors in both civilian and national security contexts, but their olfactory system remains largely unexplored in vivo. We developed and demonstrated the feasibility of an experimental setup for controlled delivery of odorant stimulus to both conscious and lightly anesthetized dogs. We found that in awake dogs, regions modulated by odor concentration were mainly in the frontal cortex, while that in anesthetized dogs were primarily in lower structures such as brain stem. The differential response to concentrations in awake and anesthetized dogs provide in vivo demonstration of previous ex vivo cellular recordings.

2900.   81 Heritability of hemodynamic response function of human brain during working memory task
Zuyao Y Shan1, Katie L McMahon1, Greig I de Zubicaray2, Paul M Thompson3, Nicholas G Martin4, Margaret J Wright4, and David C Reutens1
1Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4072, Australia, 2School of Psychology, The University of Queensland, Brisbane, QLD 4072, 3Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA, United States, 4Genetic Epidemiology Laboratory, Queensland Insitute of Medical Research, Brisbane, QLD 4029, Australia
Neurovascular coupling is crucial for normal brain function but the contribution of genetic factors to coupling mechanisms is poorly understood. We investigated the heritability of the hemodynamic response function (HRF) of BOLD fMRI in the brain using the twin methodology, in which the degree of concordance between monozygotic (MZ, identical) and dizygotic (DZ, fraternal) twin pairs is compared. We found smaller differences in HRF time to peak in MZ than DZ twin pairs. It suggests that this trait is heritable, perhaps reflecting the genetic influence on neurovascular coupling factors that control the timing of blood entry into the activated area.

2901.   82 SVM analysis of nicotine craving using functional MRI
Yash Shailesh Shah1, Luis Hernandez-Garcia1, Douglas C Noll1, Kinh Luan Phan1, Mark K Greenwald2, Jon Kar Zubieta1, and Scott J Peltier1
1University of Michigan, Ann arbor, Michigan, United States, 2Wayne State University, Detroit, Michigan, United States

Support vector machine learning from fMRI images for application in real-time neurofeedback to regulate craving in nicotine-dependent subjects.

2902.   83 Assessment of Cerebral Autoregulation by Inducing Acute Hypertension in Rats
Guang Li1,2, Yen-Yu I. Shih2, Bryan H. De La Garza2, Jeffrey W. Kiel3,4, and Timothy Q. Duong1,2
1Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 2Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 3Ophthalmology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 4Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States

There are clinical interests in dynamic cerebral autoregulation (DCA) assessment in diseases such as stroke and diabetic. We developed a rat model to assess DCA through transient BF changes during acute hypertension using MRI. We detected normal and impaired CA, and also revealed BF and oxygenation increases associated with acute BP elevation. Our study suggested that CA was established at a higher BF level during acute hypertension under normocapnia but it was impaired under hypercapnia. This method can be used for quick region-specific CA evaluation in normal and diseased physiology and can be extended to other organs such as eye.

2903.   84 Paradoxical increase in amygdala responsiveness to unpleasant stimuli through peripheral beta-blockade: a pharmacological fMRI study
Rebecca Susan Dewey1,2, Olga Pollatos3, Akram A. Hosseini1, Susan T. Francis2, and Dorothee P. Auer1
1Radiological and Imaging Sciences, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom, 2Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom, 3Department of Psychology, Potsdam University, Potsdam, Germany

Reduction of peripheral nervous system feedback is hypothesised to be associated with reduced neural response to emotional stimuli. Emotional stimuli typically elicit responses in the limbic system, including the amygdala, brainstem and salience network (anterior insula and anterior cingulate). The peripherally acting beta-blocker, nadolol, reduces peripheral autonomous nervous responses. Simultaneous acquisition of perfusion weighted ASL and BOLD fMRI give novel insight into regional drug induced changes in BOLD and perfusion. This study reports a pharmacologically induced increase in amygdala response to unpleasant emotional visual stimuli as measured using BOLD fMRI. Speculative explanations for paradoxical amygdala behaviour are given.

2904.   85 Evaluation of a new qBOLD approach to map local blood oxygen saturation in non human primates
Julien Bouvier1,2, Affif Zaccaria1,3, Irène Troprès4, Laurent Selek3,5, Pierre Bouzat3,5, David Chechin2, François Berger3,5, Alexandre Krainik3,5, and Emmanuel Barbier1,3
1INSERM, U836, Grenoble, Isère, France, 2Philips Healthcare, Suresnes, Ile de France, France, 3Université Joseph Fourier, Grenoble Institute of Neurosciences, Grenoble, France, 43T Facility, SFR Biomedical NMR and Neurosciences, Grenoble, France, 5CHU, Grenoble, France

Tissue oxygenation can be characterized by local oxygen saturation (lSO2), which may be mapped by quantitative Blood Oxygen Level Dependent (BOLD) approaches. An approach that combines separate estimates of T2, T2*, BVf, and B0 inhomogeneities has recently been proposed and validated in rats and a preliminary study has been realized in humans. The aim of this study is to evaluate this approach in non human primates under two depth of anesthesia.

2905.   86 Hemodynamics under pharmacological challenge in rat brain: comparison of BOLD, CBV and CBF using bicuculline
Zeenat Atcha1, Hui Chien Tay1, Fatima Ali Nasrallah1, Huang Wei Wei1, Brian Henry2, and Kai-Hsiang Chuang1
1Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore, Singapore, 2Medicine Research Centre, MSD, Singapore, Singapore

The aim of our study was to investigate the sensitivity and distinct spatiotemporal responses of bicuculine-induced brain activity using three pharmacological magnetic resonance imaging (phMRI) methods: blood-oxygen-level-dependent (BOLD) contrast, cerebral blood volume (CBV) with intravascular contrast agent, and cerebral blood flow (CBF) with arterial spin labeling (ASL). Acute administration of bicuculline produced region-specific hemodynamic responses in the S1, hippocampal, caudate putamen and thalamus regions. Furthermore, we demonstrate that temporal dynamics of CBV and BOLD signals were long lasting, whereas CBF responses were immediate. Information obtained from these complementary imaging techniques provide better insights to underpin neurovascular coupling upon a drug challenge.

2906.   87 Brain Oxygen Saturation assessment using T2 Prepared Diffusion Imaging
Esben Thade Petersen1, Jill De Vis1, Thomas Alderliesten2, Petra M. Lemmers2, Karina J Kersbergen2, Manon Benders2, C. A. T. van den Berg3, and Jeroen Hendrikse1
1Department of Radiology, UMC, Utrecht, Netherlands, 2Neonatology, Wilhemina Children's Hospital, Utrecht, Netherlands, 3Department of Radiotherapy, UMC, Utrecht, Netherlands

Bloods oxygen saturation is an important parameter for the evaluation of patients such as stroke or asphyxiated newborns. Here we present a method for measurement of blood T2 in the tissue using a “T2-Prepared Blood IVIM Imaging of Oxygen Saturation” (T2-BIOS) sequence from where bloods oxygen saturation can be estimated. IVIM effects in diffusion-weighted imaging are exploited to separate the blood signal and by using previous determined relationships of T2 versus Y, one can generate an oxygen saturation map. In the neonates this information is obtained from NIRS and similarity is shown, although not significantly correlated in this small population.

2907.   88 Empirical estimation of the Grubb exponent using simultaneously acquired CBF and static magnetisation changes
Kevin Murphy1, Ashley D Harris1, and Richard G Wise1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom

The Grubb exponent, α, describes the non-linear relationship between CBV and CBF changes and is usually assumed to be 0.38. Increases in CBV are reflected in the static magnetisation (M0) changes of the BOLD signal. This study proposes a model to use simultaneously acquired static magnetisation and CBF measurements to determine α. A previous model by Woolrich et al., neglected M0 effects caused by extravascular spins after CBV increases. This new model accounts for both blood and non-blood effects on M0 and removes the need to assume a baseline CBV value when estimating the Grubb exponent.

2908.   89 Measurement of absolute CMRO2 in the human brain with calibrated FMRI
Richard G Wise1, Ashley D Harris1, and Kevin Murphy1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom

We present a method for measuring absolute cerebral metabolic oxygen consumption (CMRO2). ASL and BOLD FMRI were combined with hypercapnic and hyperoxic respiratory challenges. Under an assumption of iso-metabolism, the BOLD signal calibration parameter (M) established in hypercapnia was used with the hyperoxic BOLD signal changes to estimate the resting venous deoxyhaemoglobin concentration and therefore oxygen extraction fraction and CMRO2, on a regional basis. This was performed at rest and with continuous visual stimulation. The proposed method may offer a useful marker of cerebral metabolism in health and disease given its non-invasiveness compared to radiotracer methods.

2909.   90 Quantitative measurement of functional cerebral blood volume changes with multi-echo fMRI at 7T
Swati Rane1, Manus Donahue1,2, and John C Gore1,3
1Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 2Psychiatry, Vanderbilt University, Nashville, TN, United States, 3Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Multi-echo fMRI experiments were performed at 7T with and without REST slabs. Signal changes upon functional activation were measured at TE = 0 ms as a measure of functional CBV change. Simulations were also conducted to study multi-echo fMRI signal characteristics and its dependence on functional CBV changes

2910.   91 A simple heuristic model for the BOLD response (that works remarkably well)
Valerie E.M. Griffeth1, Nicholas P Blockley2, and Richard B Buxton2
1Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States, 2Department of Radiology, University of California, San Diego, La Jolla, CA, United States

We used a detailed model of the BOLD effect to reexamine the original assumptions of the Davis model for calibrated BOLD, particularly the relationship between the BOLD signal and the change in total deoxyhemoglobin content. A simple heuristic model, as an alternative to the Davis model, incorporates transparent dependency on the underlying physiology, and works remarkably well for CBF/CMRO2 coupling ratios from 1.3-5. Additionally, it directly defines the null line of the BOLD response while also providing a means by which to directly compare CBF/CMRO2 coupling ratios between two stimuli without calibrating to measure the scaling parameter, M.

2911.   92 Dependence of Cerebral Blood Flow and Oxygen Consumption on Hyperoxia-Induced Changes in the Longitudinal Relaxation Time
David Thomas Pilkinton1, and Ravinder Reddy1
1Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

This work aims to develop a biophysical model that relates blood flow and oxygen consumption to the observed T1 decrease in tissues during hyperoxia. Showing opposite trends compared to hyperoxic effects on R2 (BOLD), hyperoxic R1 enhancement increases as CBF increases and metabolism decreases. Using hypercapnia to induce an isometabolic increase in CBF, our model captures effects on R1 due to this physiological parameter during hyperoxia. Since a comprehensive validation of this model requires measuring hyperoxia as a function of metabolism, future work will focus on altered metabolic states.

2912.   93 Hyperoxic Calibrated Quantitative fMRI for the Measurement of Regional Cerebral Metabolic Rate of Oxygen in a Hypermetabolic Swine Model
David T Pilkinton1, Victor K Babu1, Wesley Baker1, Joel H Greenberg2, and Ravinder Reddy1
1Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States

The aim of this study is to quantify relative metabolic changes using hyperoxic calibrated BOLD/ASL fMRI in a hypermetabolic swine model. Metabolic changes using this large animal model were previously studied by our group using gas that is isotopically-enriched with 17O2. We sought to cross-validate these measurements with hyperoxic dHb dilution methods of relative metabolism and to compare the results of hyperoxia and hypercapnia calibration methods using this animal model.

2913.   94 Quantification of Cerebral Arteriole Oxygenation in Human Brain by qBOLD Technique
Xiang He1, Chan-Hong Moon1, Serter Gumus1, Ayaz Aghayev1, JinHong Wang1, Dmitriy A Yablonskiy2, and Kyongtae Ty Bae1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Mallinckrodt Institute of Radiology, Washington University in St Louis, St Louis, Missouri, United States

The objective of this study is a non-invasive quantification of arteriole oxygenation in human brain in the baseline state and during functional activation. We applied a recently proposed MR-based ASL-qBOLD technique to investigate T2* decay profile of ASL water signal originated from large feeding arteries and small arteries/arterioles. Our data demonstrate a gradual decrease of arteriole blood oxygenation approaching capillaries. We found that in arterioles the mean blood oxygen saturation was 86.9±3.4%. During visual stimulation, no significant change of arteriole blood oxygenation was detected, which is consistent with the results reported in previous studies using invasive methods in rodent models.

2914.   95 Non-invasive Quantification of Absolute Cerebral Blood Volume Applicable to the Whole Human Brain
Pelin Aksit Ciris1, Maolin Qiu1, and Robert Todd Constable1
1Yale University, New Haven, CT, United States

CBV changes occur across diverse pathologies and during functional challenges, however, measurements have been invasive and difficult especially in humans. In this study, whole brain absolute CBV (mL blood/100mL parenchyma) was measured non-invasively in 13 human volunteers during visual stimulation; by further developing a method based on a biophysical model with rotating multi-slice acquisitions maintaining steady state. Such non-invasive quantification could foster improved understanding of the relationship between neuronal activity, hemodynamic changes and metabolism underlying fMRI signal, provide a reference for calibrated fMRI, and potentially find clinical utility in evaluating vascular state, vascular damage, and/or monitoring treatments.

2915.   96 Acute and chronic effects of glucose on brain metabolism: findings from healthy subjects and diseased conditions
Feng Xu1, Peiying Liu1, Juan Pascual2, Xuchen Zhang2, and Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 2Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States

The glucose is the primary source of energy for the brain and its effect on brain metabolism is not well understood. With a recently developed technique quantifying cerebral metabolic rate of oxygen (CMRO2), we studied the acute and chronic effect of glucose on healthy controls and GLUT-1 deficiency (GLUT-1 DS) patients who suffer the chronic hypoglycemia in the brain. In healthy subjects, the acute increase of glucose reduced CMRO2. The baseline CMRO2 of Glut-1DS patients is lower than healthy controls, and was elevated after the glucose ingestion.