fMRI Connectivity
Thursday 23 April 2009
Room 323ABC 16:00-18:00


Scott J. Peltier and Silvina G. Horovitz

16:00 689. Genetic Influences on Economical Properties of Human Functional Cortical Networks
    Alex Fornito1,2, Andrew Zalesky2, Danielle Bassett1, David Meunier1, Murat Yücel2, Stephen J. Wood2, Deborah Nertney3, Bryan Mowry3, Christos Pantelis2, Ed Bullmore1
Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, Cambridgeshire, UK; 2Melbourne Neuropsychiatry Centre, Department of Psychiatry, University of Melbourne, Parkville, Victoria, Australia; 3Queensland Centre for Mental Health Research, University of Queensland, Brisbane, Queensland, Australia
    The connectivity network of the human brain evolved to balance the competing priorities of maximizing efficiency of information transfer while minimizing wiring cost. In this study, we quantified the degree to which individual differences in the cost-efficiency of cortical functional networks are attributable to genetic factors using graph analytic techniques applied to resting fMRI data acquired in twins. Genetic factors accounted for approximately 91% of the variance in global network cost-efficiency, with some cortical regions under more genetic influence than others. These findings indicate that economical properties of cortical networks are highly heritable.
16:12 690. Resting-State Functional Connectivity, Probabilistic Diffusion Tensor Tractography, and Histological Delineation in the Human Thalamus
    Dongyang Zhang1, Joshua S. Shimony1, Abraham Z. Snyder1, Michael D. Fox1, Mark W. Sansbury1, Marcus E. Raichle1
Radiology, Washington University School of Medicine, Saint Louis, MO, USA
    Resting-state functional connectivity MRI (fcMRI) and diffusion weighted imaging and tractography (DTI/DTT) were performed as measures of functional and structural connectivity of the human thalamocortical system. Five ROIs were drawn in cortex corresponding to prefrontal, parietal/occipital, motor/premotor, somatosensory, and temporal cortices. Connectivity was measured between cortical ROIs and voxels in the thalamus using spontaneous neuronal activity correlations from fcMRI and probabilistic tractography from DTI. Results from these two dissimilar approaches showed remarkably similar thalamic localization. fcMRI and DTT results were compared to “gold standard” histological atlas reconstructed in 3D volume and registered to the same space as our MR results.
16:24 691. Deafferentation Induced Cross-Hemispheric Brain Plasticity Detected by Resting-State Functional Connectivity Magnetic Resonance Imaging
    Christopher Paul Pawela1,2, Bharat B. Biswal3, Rupeng Li2, Anthony G. Hudetz4, James S. Hyde2
Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA; 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA; 3Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark, NJ, USA; 4Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
    Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show neuroplasticity following peripheral nerve injury. Sub-acute brain plasticity was observed two weeks following transection of the four major nerves of the brachial plexus. Direct functional magnetic resonance imaging (fMRI) stimulation of the intact radial nerve reveals an activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. The combination of fMRI and fcMRI provides a general marker for brain plasticity and may provide insight into phantom limb epiphenomena.
16:36 692. Functional MRI of Somatosensory Cortical Reorganization in the Rat Brain
    Xin Yu1, Shumin Wang1, Stephen Dodd1, Der-yow Chen1, Alan Koretsky1
National Institutue of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
    A 3D somatotopic map in the rat primary somatosensory cortex (S1) was characterized with BOLD-fMRI, including forepaw, hindpaw, whisker pad, and nose S1 regions. These maps enabled analysis of the topographic cortical reorganization following sensory deprivation of the whisker barrel cortex. It is well known that functional MRI maps vary largely depending on the t-threshold used. Here we show that the location of center of mass in S1 subdivisions is highly consistent regardless of t statistics. Utilizing mass-center as anchor points to model BOLD response enabled a quantitative analysis of cortical reorganization in the rat brain with BOLD-fMRI.
16:48 693. Intrinsically Organized Low Frequency Network for Face Perception
    Zhang hui1, Tian Jie*1
Institute of automation Chinese Academy of Sciences , Beijing, China
    For the first time, we investigated the low-frequency fluctuations of distributed face perception network in resting states and the modulation of this network from resting to face viewing task. By using 0.01-0.08HZ low-frequency spontaneous fluctuations of BOLD-fMRI signals, Our result suggested an intrinsically organized low-frequency face perception network involving right lateral posterior fusiform gyrus (lateral pFg), inferior occipital gyrus (IOG), bilateral superior temporal sulcus (STS) and an altered extended network for face perception from resting states to face viewing task.
17:00 694. Spectral Clustering of Low-Frequency Fluctuations in FMRI Data Reveal a Distinct Separation Between the Superior Temporal Sulcus and the Superior Temporal Gyrus
    Gabriele Lohmann1, Jonas Obleser1, Angela Friederici1, Robert Turner1
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
    Low Frequency Fluctuations (LFFs) are known to represent a large portion of the variance of the BOLD signal. Furthermore, such fluctuations generally have significant spatial coherence. Task-dependent condition-locked fMRI data has confirmed an important role of the superior temporal cortex in many language and hearing related processes. Within this area, many studies have claimed to identify activation distinct to superior temporal gyrus (STG) and superior temporal sulcus (STS). Using a data-driven clustering technique applied to LFFs, we found a clear separation between STS and STG that showed a high inter-subject consistency.
17:12 695. Integration and Comparison of Brain Functional and Structural Connectivity Maps
    David C. Zhu1, Shantanu Majumdar2
Psychology and Radiology, Michigan State University, East Lansing, MI, USA; 2Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
    Resting-state fMRI allows the testing of brain functional connectivity. Diffusion tensor imaging fiber tracking allows the evaluation of structural connection between cortical regions. Often there is a need to integrate them together to understand the networks of brain activity, to compare their advantages and disadvantages, and to evaluate potential applications. In this work, we combined the functional and structural connectivity maps based on common seed regions. The integration demonstrates potential interpretation issues and also shows that functional connectivity might be a more sensitive and robust technique in understanding the connectivity between cortical regions.
17:24 696. An FMRI Study of Induced Plasticity in S1 in the Human Brain
    rishma vidyasagar1, Laura Parkes2
MARIARC, University of Liverpool, Liverpool, Merseyside, UK; 2School of Cancer and Imaging Sciences, manchester, UK
    This study measured induced connectivity in the human brain on S1 between Digit 2 and Digit 4 of the right hand using fMRI. Cortical reorganisation was induced by training subjects on vibrotactile tactors for 3 hours. Subjects were scanned before and after training and cortical representations of the digits were successfully imaged. Significant shifts and overlap of these areas were observed following the training period. This is in accordance with previous animal and human studies. It is postulated that what is observed are changes linked to synchronised synaptic input and can be related to Hebbian mechanisms.
17:36 697. Analysis of Changes in Functional Connectivity Patterns with Serial Resting State FMRI After Transient Ischemic Stroke in Rat Brain
    Kajo van der Marel1, Maurits P. A. van Meer1,2, Kun Wang3, Willem Maarten Otte1, Jan Willem Berkelbach van der Sprenkel2, Rick M. Dijkhuizen1
Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands; 3Institute of Automation, Chinese Academy of Sciences, Beijing, China
    Resting state fMRI analysis provides a method to measure changes in functional connectivity within various neural networks without the need of stimulating a specific functional system. These functional networks may be altered during recovery from stroke. In this study we found differences in functional connectivity pattern dependent on time and lesion size after transient stroke in rats. Loss and recovery of functional connectivity within bilateral sensorimotor network areas were indicative of functional brain reorganization after stroke.
17:48 698. Connectivity Alterations in Motor-Related Areas Suggest Neuroplasticity in Chronic Stroke
    Dionyssios Mintzopoulos1,2, Loukas G. Astrakas1,3, Azadeh Khanicheh4, Angelos A. Konstas5, Michael A. Moskowitz2,6, Bruce R. Rosen5, A. Aria Tzika1,2
NMR Surgical Laboratory, MGH & Shriners Hospitals, Harvard Medical School, Boston, MA, USA; 2Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA; 3Medical Physics, University of Ioannina, Ioannina, Greece, USA; 4Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA; 5Radiology, MGH, Harvard Medical School, Boston, MA, USA; 6Neuroscience Center, Neurology and Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
    Using a hand motor task, we investigated functional reorganization of motor systems by probing connectivity between motor related areas in chronic stroke patients undergoing training with functional magnetic resonance imaging (fMRI) at 3T combined with a novel MR-compatible hand-induced robotic device (MR_CHIROD). The results demonstrate that rehabilitation training enhances the connectivity between motor areas in chronic stroke patients that may help counterbalance a functionally abnormal M1 motor area in stroke patients thus suggesting neuroplasticity in chronic stroke.