ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Scientific Session: Structural/Functional Connectomics

Thursday, May 12, 2016
Hall 606
13:30 - 15:30
Moderators: Victoria Morgan, Jay Pillai

Bayesian Exponential Random Graph Modeling of Whole-Brain Structural Networks across Lifespan
Michel R.T. Sinke1, Willem M. Otte1,2, Alberto Caimo3, Cornelis J. Stam4, and Rick M. Dijkhuizen1
1Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands, 2Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands, 3Social Network Analysis Research Centre, Interdisciplinary Institute of Data Science, University of Lugano, Lugano, Switzerland, 4Department of Clinical Neurophysiology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, Netherlands
Comparison of brain networks that differ in size or edge density may be inadequate with frequently applied descriptive graph analysis methods. To resolve this, we propose an alternative framework based on Bayesian generative modeling, allowing unbiased assessment of local substructures that shape the global network topology. Structural networks were derived from DTI-based whole-brain tractography of 382 healthy subjects (age: 20-86 years), and successfully simulated. Despite clear effects of age and hub damage on network topologies, relative contributions of local substructures did not change significantly. The use of generative models may shed new light on the complex (re)organization of the brain.

Resting state fMRI of spinal cord is keeping synchronistic with brain - Permission Withheld
Jinsong Zhang1, Lingzhi Wang2, and Jun Li2
1Radiology department,Xijing Hospital, MRI room, Xi'an, China, People's Republic of, 2School of Life Science and Technology, Xidian University, Xi'an, China, People's Republic of
The spinal cord and brain form central nervous system and sensory and motor signals are relayed by spinal cord and processed by brain. Studies have suggested that resting state functional connectivity (rsFC) are fundamental, common feature of the entire nervous system. However, it still remain unknown the correlation between rsFCs within spinal cord and brain. The present study discovered dorsal and ventral resting state networks (RSNs) within spinal cord and sensory-motor RSN within brain. Further, correlation analysis suggest that dorsal and ventral RSNs connected to sensory and motor RSNs respectively. 

Functional connectivity self-regulation of cerebellum and primary motor area with fMRI-Brain Computer Interfaces. Pilot results.
Patricia Andrea Vargas1,2, Ranganatha Sitaram1,3,4,5, Pradyumna Sepúlveda2,6, Cristian Montalba2, Mohit Rana1, Cristián Tejos2,6, and Sergio Ruiz1,3
1Department of Psychiatry, Faculty of Medicine, Interdisciplinary Center for Neuroscience, Pontificia Universidad Católica de Chile, Santiago, Chile, 2Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, 3Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany, 4Sree Chitra Tirunal Institute of Medical Sciences and Technology, Trivandrum, India, 5Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, 6Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
In recent years there is a growing interest in the potential application of Brain-Computer interfaces (BCI) for psychiatric and neurological disorders. After stroke, if the primary motor cortex (M1) is affected, it is common to find a “deactivation” of the contralateral cerebellum.

The aim of this study was to evaluate  the feasibility of achieving volitional control of M1-cerebellum functional connectivity, in healthy subjects with an fMRI-BCI system.

The results indicate that volitional self-regulation of cerebellum-M1 connectivity is feasible with fMRI-BCI. The data also suggests that cerebellum is more easily recruited than M1.

Connectivity-based parcellation of nucleus accumbens into putative core and shell guiding for stereotactic target localization and alterations in each NAc subdivision in mTLE patients
Xixi Zhao1, Junling Wang1, Xiangliang Tan1, Xiang Xiao1, Zeyu Zheng1, Yingjie Mei2, Queenie Chan3, Yikai Xu1, Ru Yang4, and Qianjin Feng4
1Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China, People's Republic of, 2Philips Healthcare, Guangzhou, China, People's Republic of, 3Philips Healthcare, HongKong, China, People's Republic of, 42School of Biomedical Engineering and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China, People's Republic of
NAc was supposed be involved in epileptogenesis, especially shell portion. The exact parcellation within the NAc and structural alterations in vivo of NAc subdivisions in EP patients remains unclear. We used diffusion probabilistic tractography to subdivide NAc into putative core shell subdivisions in individual mTLE patients for guiding NAc shell stereotactic target localization. Our results revealed that both left and right mTLE patients exhibited decreased FA and increased MD in shell portion of bilateral NAc, which may reflect neuronal degeneration and damage caused by seizure mainly in shell portions, and suggest a possible role of the NAc shell in epileptogenesis

Brain White Matter Plasticity and Functional Reorganization Underlying the Central Pathogenesis of Idiopathic Trigeminal Neuralgia
Linying Guo1, Tian Tian1, and Wenzhen Zhu1
1Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China, People's Republic of
Previous studies on trigeminal neuralgia (TN) have mainly focused on peripheral nerve damage, but little is known about the structural and functional changes in central nervous system (CNS) that can occur following trigeminal nerve dysfunction. In this study, we used diffusion kurtosis imaging (DKI) and functional connectivity density (FCD) mapping in TN patients to investigate both structural and functional changes in CNS. We found TN patients have correlated white matter and FCD reorganization that may contribute to pathologic algogenic system. Our findings may be helpful guidance for systematic therapeutics in both peripheral and central nerves.

Connectivity Domain Analysis of the Default Mode Network in Mild Traumatic Brain Injury at The Acute Stage
Armin Iraji1, Natalie Wiseman2, Robert Welch3, Brian O'Neil3, E. Mark Haacke1,4, and Zhifeng Kou1,4
1Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States, 2Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, United States,3Department of Emergency Medicine, Wayne State University, Detroit, MI, United States, 4Department of Radiology, Wayne State University, Detroit, MI, United States
Most functional and structural MRI studies in mild traumatic brain injury (mTBI) are performed at the group level. Recently, there is concern regarding the validity of group-level analyses findings in mTBI due to the heterogeneity of TBI. However, while group-level analysis cannot demonstrate a complete view of impairments, we hypothesize that there are similar patterns in group-level and subject-level findings, especially in higher order brain activities and networks. We evaluated this in the DMN using a new framework known as the connectivity domain. This is the first study of utilizing the connectivity domain to investigate changes after a brain disorder.

Brain connectivity of glioblastoma patients using MR-PET and DTI data
Ana Carina Mendes1, Ana-Maria Oros-Peusquens2, André Santos Ribeiro1,3, Karl-Josef Langen2, Carolin Weiß Lucas4, Nadim Jon Shah2, and Hugo Alexandre Ferreira1
1Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal, 2Forschungszentrum Juelich GmbH, Institute of Neurosciences and Medicine-INM4, Juelich, Germany, 3Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom, 4Center of Neurosurgery, University of Cologne, Cologne, Germany
Methods capable of mapping brain connectivity pathways may prove useful by providing valuable information in order to prevent sequelae following a surgical intervention. This study presents an approach for the whole-brain connectivity evaluation of nine patients with lateralized gliobastoma, using the Multimodal Imaging Brain Connectivity Analysis (MIBCA) toolbox to process MR and PET data. Results show changes in connectivity metrics across both hemispheres for all patients accompanied by an increased number of fibres which may result from reorganization of connectivity pathways caused by the disruption of the original ones by the tumour.

Thresholding to Improve the Specificity of High Spatial and Angular Resolution In Vivo Diffusion-Weighted Tractography to Estimate Brain Stem Connectivity.
Matthew Hey1, Luis Colon-Perez2, William Triplett3, David Fitzgerald4, and Thomas Mareci5
1University of Florida, Gainesville, FL, United States, 2Department of Psychiatry, University of Florida, Gainesville, FL, United States, 3Department of Physical Therapy, University of Florida, Gainesville, FL, United States, 4Department of Neurology, University of Florida College of Medicine, Gainesville, FL, United States, 5Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, United States
The spatial resolution of diffusion-weighted (DWI) images limits the white matter streamline fiber tracks, which can be followed in the brain stem. To address this issue, we introduce a high spatial resolution protocol and the use of a threshold to limit the false positive in streamline track density maps by requiring that a minimum amount of fibers pass through a voxel. This provides increased accuracy in the visualization of streamlines connecting specific regions of the brain stem and may allow the recognition of structural abnormalities due to neurological diseases.  

Influence of repetitive transcranial magnetic stimulation on functional connectivity and hemodynamics in the rat brain
Julia Boonzaier1, Geralda A. F. van Tilborg1, Mark J.R.J. Bouts2,3,4, Petar P.I. Petrov5, Caroline L. van Heijningen1, Gerard van Vliet1, Annette van der Toorn1, Sebastiaan F.W. Neggers5, and Rick M. Dijkhuizen1
1Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands, 2Institute of Psychology, Leiden University, Leiden, Netherlands, 3Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 4Leiden Institute for Brain and Cognition (LIBC), Leiden University, Leiden, Netherlands, 5Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique with the ability to change cortical excitability, however its precise mechanism of action is not completely understood. Therefore, by acquiring resting-state fMRI and perfusion MRI data we assessed the influence of unilateral low-frequency (inhibitory) rTMS on functional connectivity and hemodynamics instimulated cortical tissue in rats. After four consecutive days of rTMS we measured reduced interhemispheric functional connectivity between homotopic sensorimotor regions, while cerebral blood flow remained largely unaffected. This reduction in interhemispheric functional connectivity may be due to the inhibitory effect of low-frequency rTMS on cortical excitability. 

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