title: Introducing co-activation pattern metrics to quantify spontaneous brain network dynamics.
abstract: Recently, fMRI researchers have begun to realize that the brain's intrinsic network patterns may undergo substantial changes during a single resting state (RS) scan. However, despite the growing interest in brain dynamics, metrics that can quantify the variability of network patterns are still quite limited. Here, we first introduce various quantification metrics based on the extension of co-activation pattern (CAP) analysis, a recently proposed point-process analysis that tracks state alternations at each individual time frame and relies on very few assumptions; then apply these proposed metrics to quantify changes of brain dynamics during a sustained 2-back working memory (WM) task compared to rest. We focus on the functional connectivity of two prominent RS networks, the default-mode network (DMN) and executive control network (ECN). We first demonstrate less variability of global Pearson correlations with respect to the two chosen networks using a sliding-window approach during WM task compared to rest; then we show that the macroscopic decrease in variations in correlations during a WM task is also well characterized by the combined effect of a reduced number of dominant CAPs, increased spatial consistency across CAPs, and increased fractional contributions of a few dominant CAPs. These CAP metrics may provide alternative and more straightforward quantitative means of characterizing brain network dynamics than time-windowed correlation analyses.
authors: Department of Radiology, Stanford University, Stanford, CA 94305, USA; Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA. Electronic address: cjy2010@stanford.edu.
authors: Jingyuan E
authors: JE
authors: Chen
authors: Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Catie
authors: C
authors: Chang
authors: Functional Imaging in Neuropsychiatric Disorders Lab, Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA 94305, USA.
authors: Michael D
authors: MD
authors: Greicius
authors: Department of Radiology, Stanford University, Stanford, CA 94305, USA.
authors: Gary H
authors: GH
authors: Glover
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D009415:Nerve Net / Q000502:physiology*; D012146:Rest / Q000502:physiology
keywords: Brain dynamics; Co-activation patterns; Point process analysis; Resting state networks; Working memory