title: Investigating directed cortical interactions in time-resolved fMRI data using vector autoregressive modeling and Granger causality mapping.
abstract: We present a framework aimed to reveal directed interactions of activated brain areas using time-resolved fMRI and vector autoregressive (VAR) modeling in the context of Granger causality. After describing the underlying mathematical concepts, we present simulations helping to characterize the conditions under which VAR modeling and Granger causality can reveal directed interactions from fluctuations in BOLD-like signal time courses. We apply the proposed approach to a dynamic sensorimotor mapping paradigm. In an event-related fMRI experiment, subjects performed a visuomotor mapping task for which the mapping of two stimuli ("faces" vs "houses") to two responses ("left" or "right") alternated periodically between the two possible mappings. Besides expected activity in sensory and motor areas, a fronto-parietal network was found to be active during presentation of a cue indicating a change in the stimulus-response (S-R) mapping. The observed network includes the superior parietal lobule and premotor areas. These areas might be involved in setting up and maintaining stimulus-response associations. The Granger causality analysis revealed a directed influence exerted by the left lateral prefrontal cortex and premotor areas on the left posterior parietal cortex.
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology, Maastricht University, Maastricht, The Netherlands. r.goebel@psychology.unimaas.nl
authors.forename: Rainer
authors.initials: R
authors.lastname: Goebel
authors.forename: Alard
authors.initials: A
authors.lastname: Roebroeck
authors.forename: Dae-Shik
authors.initials: DS
authors.lastname: Kim
authors.forename: Elia
authors.initials: E
authors.lastname: Formisano
mesh_terms: D001931:Brain Mapping; D015984:Causality; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D011597:Psychomotor Performance; D012044:Regression Analysis