title: Identifying Sparse Connectivity Patterns in the brain using resting-state fMRI.
abstract: The human brain processes information via multiple distributed networks. An accurate model of the brain's functional connectome is critical for understanding both normal brain function as well as the dysfunction present in neuropsychiatric illnesses. Current methodologies that attempt to discover the organization of the functional connectome typically assume spatial or temporal separation of the underlying networks. This assumption deviates from an intuitive understanding of brain function, which is that of multiple, inter-dependent spatially overlapping brain networks that efficiently integrate information pertinent to diverse brain functions. It is now increasingly evident that neural systems use parsimonious formations and functional representations to efficiently process information while minimizing redundancy. Hence we exploit recent advances in the mathematics of sparse modeling to develop a methodological framework aiming to understand complex resting-state fMRI connectivity data. By favoring networks that explain the data via a relatively small number of participating brain regions, we obtain a parsimonious representation of brain function in terms of multiple "Sparse Connectivity Patterns" (SCPs), such that differential presence of these SCPs explains inter-subject variability. In this manner the sparsity-based framework can effectively capture the heterogeneity of functional activity patterns across individuals while potentially highlighting multiple sub-populations within the data that display similar patterns. Our results from simulated as well as real resting state fMRI data show that SCPs are accurate and reproducible between sub-samples as well as across datasets. These findings substantiate existing knowledge of intrinsic functional connectivity and provide novel insights into the functional organization of the human brain.
authors.affiliation: Center for Biomedical Image Computing and Analytics, University of Pennsylvania, USA. Electronic address: Harini.Eavani@uphs.upenn.edu.
authors.forename: Harini
authors.initials: H
authors.lastname: Eavani
authors.affiliation: Center for Biomedical Image Computing and Analytics, University of Pennsylvania, USA; Brain Behavior Laboratory, Department of Psychiatry, University of Pennsylvania, USA.
authors.forename: Theodore D
authors.initials: TD
authors.lastname: Satterthwaite
authors.affiliation: Center for Biomedical Image Computing and Analytics, University of Pennsylvania, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Filipovych
authors.affiliation: Brain Behavior Laboratory, Department of Psychiatry, University of Pennsylvania, USA.
authors.forename: Raquel E
authors.initials: RE
authors.lastname: Gur
authors.affiliation: Brain Behavior Laboratory, Department of Psychiatry, University of Pennsylvania, USA.
authors.forename: Ruben C
authors.initials: RC
authors.lastname: Gur
authors.affiliation: Center for Biomedical Image Computing and Analytics, University of Pennsylvania, USA.
authors.forename: Christos
authors.initials: C
authors.lastname: Davatzikos
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D055815:Young Adult
keywords: Functional connectivity; Resting state fMRI; Sparsity