The Journal of Neuroscience, December 17, 2008, 28(51):13754-13764; doi:10.1523/JNEUROSCI.4544-08.2008
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Behavioral/Systems/Cognitive
Regional Variation in Interhemispheric Coordination of Intrinsic Hemodynamic Fluctuations
David E. Stark,1,2
Daniel S. Margulies,3
Zarrar E. Shehzad,1
Philip Reiss,1
A. M. Clare Kelly,1
Lucina Q. Uddin,1
Dylan G. Gee,1
Amy K. Roy,1
Marie T. Banich,4
F. Xavier Castellanos,1,5 and
Michael P. Milham1
1Phyllis Green and Randolph C
wen Institute for Pediatric Neuroscience at the New York University Child Study Center, New York, New York 10016, 2Harvard Medical School, Boston, Massachusetts 02115, 3Berlin School of Mind and Brain, 10099 Berlin, Germany, 4Department of Psychology, University of Colorado, Boulder, Colorado 80309, and 5Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
Correspondence should be addressed to either of the following: David E. Stark or Michael P. Milham, 215 Lexington Avenue, 14th Floor, New York, NY 10016. Email: davidestark{at}gmail.com or Email: michael.milham{at}nyumc.org
Electrophysiological studies have long demonstrated a high degree of correlated activity between the left and right hemispheres, however little is known about regional variation in this interhemispheric coordination. Whereas cognitive models and neuroanatomical evidence suggest differences in coordination across primary sensory-motor cortices versus higher-order association areas, these have not been characterized. Here, we used resting-state functional magnetic resonance imaging data acquired from 62 healthy volunteers to examine interregional correlation in spontaneous low-frequency hemodynamic fluctuations. Using a probabilistic atlas, we correlated probability-weighted time series from 112 regions comprising the entire cerebrum. We then examined regional variation in correlated activity between homotopic regions, contrasting primary sensory-motor cortices, unimodal association areas, and heteromodal association areas. Consistent with previous studies, robustly correlated spontaneous activity was noted between all homotopic regions, which was significantly higher than that between nonhomotopic (heterotopic and intrahemispheric) regions. We further demonstrated substantial regional variation in homotopic interhemispheric correlations that was highly consistent across subjects. Specifically, there was a gradient of interhemispheric correlation, with highest correlations across primary sensory-motor cortices (0.758, SD = 0.152), significantly lower correlations across unimodal association areas (0.597, SD = 0.230) and still lower correlations across heteromodal association areas (0.517, SD = 0.226). These results demonstrate functional differences in interhemispheric coordination related to the brain's hierarchical subdivisions. Synchrony across primary cortices may reflect networks engaged in bilateral sensory integration and motor coordination, whereas lower coordination across heteromodal association areas is consistent with functional lateralization of these regions. This novel method of examining interhemispheric coordination may yield insights regarding diverse disease processes as well as healthy development.
Key words: interhemispheric; synchrony; functional MRI; connectivity; lateralization; hemisphere; coordination
Received Sept. 22, 2008;
accepted Oct. 22, 2008.
Correspondence should be addressed to either of the following: David E. Stark or Michael P. Milham, 215 Lexington Avenue, 14th Floor, New York, NY 10016. Email: davidestark{at}gmail.com or Email: michael.milham{at}nyumc.org
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