Functional Connectivity: Mechanisms & Applications
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Wednesday May 11th
Room 510  16:00 - 18:00 Moderators: Catherine Chang and Richard Wise

16:00 428.   White matter cerebral blood flow is inversely correlated with structural and functional connectivity in the human brain 
Sina Aslan1,2, Hao Huang1,2, Jinsoo Uh1, Virendra Mishra1,2, Guanghua Xiao3, Matthias van Osch4, and Hanzhang Lu1,2
1Advanced Imaging Research Center, University of Texas at Southwestern Medical Center, Dallas, TX, United States, 2Biomedical Engineering Graduate Program, University of Texas at Southwestern Medical Center, Dallas, TX, United States, 3Division of Biostatistics, Department of Clinical Sciences, University of Texas at Southwestern Medical Center, Dallas, TX, United States, 4Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

Some evidence has suggested that gray matter functional connectivity is supported by structural connections via white matter fiber tracts. We therefore further hypothesized that functional measures of the white matter, e.g. perfusion, may have a more direct link to gray matter connectivity. Here we used ASL and DTI to measure fiber tract-specific CBF and compared it to fcMRI connectivity in the terminal gray matter. Across fiber tracts, CBF showed a paradoxically inverse correlation with FA. An inverse correlation was also observed between tract-specific CBF and the functional connectivity in the gray matters connected by the tract.

16:12 429.   Forty Weeks of Rest: An Investigation into Functional Network Stability 
Suresh Emmanuel Joel1,2, Craig K Jones1,2, Brian S Caffo3, Peter C M van Zijl1,2, and James J Pekar1,2
1Radiology, Johns Hopkins University, Baltimore, MD, United States, 2FM Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Biostatistics, Johns Hopkins University, Baltimore, MD, United States

Resting state functional connectivity data were acquired in one participant over forty weekly sessions, to estimate intra-subject variability of functional networks. Spatial independent component analysis using temporal concatenation yielded fourteen functional networks. Using between-network connectivity, networks were classified into three classes: exteroceptive (attention, somatosensory, motor, visual, and auditory), default (default mode network and fronto-parietal), and dorsal streams (right and left dorsal stream). Default networks were more stable than exteroceptive networks, and were more connected to one another than to exteroceptive networks; the more variable exteroceptive networks were more connected to one another than to default networks.

16:24 430.   Symmetry of Resting-State Functional Connectivity in FMRI: High Correlation Across Hemispheres Exists with or without Callosal Connection 
Hang Joon Jo1, Ziad S Saad1, Steve J Gotts2, Richard C Reynolds1, Patricia Christidis1, Daniel R Glen1, Alex Martin2, and Robert W Cox1
1Statistical and Scientific Computing Core, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States, 2Cognitive Neuropsychology Section, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States

We evaluate the fine organization of cross-hemispheric correlations maps in a variety of brain regions outside somatotopic cortex, including occipital, temporal, and prefrontal areas. We find that the fine-grained nature of the symmetric correlation maps carries over more generally to these other areas of cortex. However, we also find that this property carries over equally well to parts of primary visual cortex that have no direct callosal connections, namely the cortex along the depth of the calcarine sulcus that represents the horizontal meridian in V1. Our results highlight the importance of considering alternative mechanisms even in circumstances in which callosal connections are indeed plausible.

16:36 431.   BOLD Resting State Networks in Adults with Complete Callosal Agenesis 
Julian Michael Tyszka1, Lynn K Paul2, and Ralph Adolphs1,2
1Biology, California Institute of Technology, Pasadena, CA, United States, 2Humanities and Social Sciences, California Institute of Technology, Pasadena, CA, United States

The impact of agenesis of the corpus callosum on resting state connectivity in the human brain is largely unknown. In this study, we apply well-established probabilistic independent component analysis (PICA) methods to BOLD fMRI time course data in a minimum deformation space to identify spatial independent components unique to and absent in callosal agenesis. Over 80% of neurotypical BOLD resting state networks identified by group PICA are preserved in adult AgCC subjects suggesting that compensatory networks established during brain development play a major role in this condition.

16:48 432.   Investigating the Dependence of Spontaneous Fluctuations in Visual Cortex on Callosal Connectivity 
Li-Wei Kuo1, Zhongming Liu1, Jacco A. de Zwart1, Peter van Gelderen1, and Jeff H. Duyn1
1Advanced MRI section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States

In this study, we investigated the dependence of spontaneous fMRI activity in human visual cortex on callosal connectivity. Interhemispheric correlations in fMRI studies of spontaneous activity have been partly attributed to cortico-cortical connections through the corpus callosum, suggesting these correlations may be reduced in the part of visual area V1 that lacks these connections. Using 7T fMRI, regions of interest with high and low/absent callosal V1 connectivity were identified with retinotopic mapping, after which interhemispheric correlations were calculated during rest. Our preliminary results show that interhemispheric functional connectivity is organized retinotopically, with a minimal dependence on mono-synaptic callosal connectivity. This suggests that interhemispheric functional connectivity partly arises from multi-synaptic pathways.

17:00 433.   Caffeine causes widespread decreases in resting-state BOLD connectivity and energy 
Chi Wah Wong1, Valur Olafsson1, Omer Tal1, and Thomas T Liu1
1Center for Functional MRI, University of California San Diego, La Jolla, CA, United States

Previous studies have shown that caffeine reduces resting state BOLD connectivity in the motor cortex, regions in the default mode network, and the thalamus. In this study, we show that the caffeine-induced reductions in BOLD connectivity and energy are widespread, spanning multiple brain regions. Specifically, the mean network degree, which is a measure of the average number of links between brain regions, is significantly reduced by caffeine.

17:12 434.   Differential effects of opioid analgesics on functional connectivity of cortical-subcortical networks in humans 
Richard G Wise1, Anna Jolly2, Kevin Murphy1, C John Evans1, and Judith E Hall2
1CUBRIC, School of Psychology, Cardiff University, Cardiff, S. Glamorgan, United Kingdom, 2Department of Anaesthetics and Intensive Care Medicine, School of Medicine, Cardiff University, Cardiff, S. Glamorgan, United Kingdom

Opioids decrease pain-related signals in line with their analgesic effects but also modify cerebral blood flow in a pattern consistent with their receptor distribution. We examined the effect of acute mu-opioid agonist (remifentanil) administration on functional connectivity in BOLD FMRI signals. Functional connectivity (temporal covariation of BOLD signal) was increased between brainstem and anterior cingulate/insular cortex consistent with an influence of higher cortical centres on the pain-control regions of the brainstem. Conversely functional connectivity between basal ganglia (putamen) and sensorimotor cortex was reduced, a potential reflection of the drug’s sedative effects.

17:24 435.   Prediction of Age Using Resting-State Functional and Effective Connectivity 
Zhihao Li1, John A Sexton1, Gopikrishna Deshpande2, and Xiaoping Hu1
1Biomedical Engineering, Emory University & Georgia Institute of Technology, Atlanta, GA, United States, 2Electrical and Computer Engineering, Auburn University, Auburn, AL, United States

Using resting-state fMRI, support-vector-machine based multivariate pattern analysis recently shows capability of accurate predictions about brain maturity. However, with more information about inter-regional causal influences, effective connectivity may possess more power in characterizing the development of neural networks. The present study compared age prediction of these two approaches and showed a relatively better performance with effective connectivity.

17:36 436.   Left lateralization of motor circuit connectivity is associated with better motor performance in children 
Anita Dyan Barber1,2, Suresh E Joel1, Priti Srinivasan2, Simona Spinelli2, Jim J Pekar1,2, and Stewart H Mostofsky1,2
1Johns Hopkins School of Medicine, Baltimore, MD, United States, 2Kennedy Krieger Institute, Baltimore, MD, United States

The association between resting state functional connectivity within the motor network (Mostofsky et al., 2009) and motor abilities was examined. Motor performance was assessed using the PANESS (Denckla, 1985), a standardized battery sensitive to developmental changes in motor abilities. 40 typically-developing, right-handed children (ages 8-12) performed the PANESS outside of the scanner and then were scanned during a 5 minute rest session. Greater mean connectivity within the left than right hemisphere motor circuit was significantly correlated with better motor performance. The results suggest that greater left hemisphere dominance in motor circuit connectivity is associated with better motor performance in children.

17:48 437.   Functional connectivity MRI reveals memory networks after maze learning in rodents 
Fatima Ali Nasrallah1, Chen Yow Der-Yow2, Aryeh Routtenberg3, and Kai-Hsiang Chuang4
1Lab of Molecular Imaging, A*Star Biomedical Research Institutes, Buona Vista, Singapore, Singapore, 2NIH, NINDS, 3Northwestern University, 4A*Star Biomedical Research Institutes

Functional connectivity MRI has emerged as a means to map intrinsic brain networks without the need of explicit tasks. We investigated mapping plasticity of the rodent brain after a memory task using Morris water maze. Extensive and enhanced connectivity was seen in trained rats compared to swim controls, and was maintained even seven days after training. This is the first demonstration of brain plasticity following a cognitive task can be detected in the anesthetized rat using functional connectivity MRI.