title: Functional network overlap as revealed by fMRI using sICA and its potential relationships with functional heterogeneity, balanced excitation and inhibition, and sparseness of neuron activity.
abstract: Functional magnetic resonance imaging (fMRI) studies traditionally use general linear model-based analysis (GLM-BA) and regularly report task-related activation, deactivation, or no change in activation in separate brain regions. However, several recent fMRI studies using spatial independent component analysis (sICA) find extensive overlap of functional networks (FNs), each exhibiting different task-related modulation (e.g., activation vs. deactivation), different from the dominant findings of GLM-BA. This study used sICA to assess overlap of FNs extracted from four datasets, each related to a different cognitive task. FNs extracted from each dataset overlapped with each other extensively across most or all brain regions and showed task-related concurrent increases, decreases, or no changes in activity. These findings indicate that neural substrates showing task-related concurrent but different modulations in activity intermix with each other and distribute across most of the brain. Furthermore, spatial correlation analyses found that most FNs were highly consistent in spatial patterns across different datasets. This finding indicates that these FNs probably reflect large-scale patterns of task-related brain activity. We hypothesize that FN overlaps as revealed by sICA might relate to functional heterogeneity, balanced excitation and inhibition, and population sparseness of neuron activity, three fundamental properties of the brain. These possibilities deserve further investigation.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America.
authors.forename: Jiansong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America; The Mind Research Network, Albuquerque, New Mexico, United States of America; Dept of ECE, The University of New Mexico, Albuquerque, New Mexico, United States of America.
authors.forename: Vince D
authors.initials: VD
authors.lastname: Calhoun
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Worhunsky
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America; Dept of Psychiatry, Guizhou Provincial People's Hospital, Guiyang, Guizhou Province, P. R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiang
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America; Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: Dept of Neurosciences, University of Toledo, Toledo, Ohio, United States of America.
authors.forename: John T
authors.initials: JT
authors.lastname: Wall
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America; Olin Neuropsychiatry Research Center, Institute of Living, Hartford, Connecticut, United States of America.
authors.forename: Godfrey D
authors.initials: GD
authors.lastname: Pearlson
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America; Child Study Center, Yale University School of Medicine, New Haven, Connecticut, United States of America; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America.
authors.forename: Marc N
authors.initials: MN
authors.lastname: Potenza
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D016208:Databases, Factual; D066264:Datasets as Topic; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000502:physiology*; D055815:Young Adult