title: Regional variation in interhemispheric coordination of intrinsic hemodynamic fluctuations.
abstract: 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.
authors.affiliation: Phyllis Green and Randolph Cōwen Institute for Pediatric Neuroscience at the New York University Child Study Center, New York, New York 10016, USA. davidestark@gmail.com
authors.forename: David E
authors.initials: DE
authors.lastname: Stark
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Margulies
authors.forename: Zarrar E
authors.initials: ZE
authors.lastname: Shehzad
authors.forename: Philip
authors.initials: P
authors.lastname: Reiss
authors.forename: A M Clare
authors.initials: AM
authors.lastname: Kelly
authors.forename: Lucina Q
authors.initials: LQ
authors.lastname: Uddin
authors.forename: Dylan G
authors.initials: DG
authors.lastname: Gee
authors.forename: Amy K
authors.initials: AK
authors.lastname: Roy
authors.forename: Marie T
authors.initials: MT
authors.lastname: Banich
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Castellanos
authors.forename: Michael P
authors.initials: MP
authors.lastname: Milham
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply* / Q000502:physiology*; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology; D015986:Confounding Factors, Epidemiologic; D017352:Echo-Planar Imaging; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult