title: Investigating the neural basis for functional and effective connectivity. Application to fMRI.
abstract: Viewing cognitive functions as mediated by networks has begun to play a central role in interpreting neuroscientific data, and studies evaluating interregional functional and effective connectivity have become staples of the neuroimaging literature. The neurobiological substrates of functional and effective connectivity are, however, uncertain. We have constructed neurobiologically realistic models for visual and auditory object processing with multiple interconnected brain regions that perform delayed match-to-sample (DMS) tasks. We used these models to investigate how neurobiological parameters affect the interregional functional connectivity between functional magnetic resonance imaging (fMRI) time-series. Variability is included in the models as subject-to-subject differences in the strengths of anatomical connections, scan-to-scan changes in the level of attention, and trial-to-trial interactions with non-specific neurons processing noise stimuli. We find that time-series correlations between integrated synaptic activities between the anterior temporal and the prefrontal cortex were larger during the DMS task than during a control task. These results were less clear when the integrated synaptic activity was haemodynamically convolved to generate simulated fMRI activity. As the strength of the model anatomical connectivity between temporal and frontal cortex was weakened, so too was the strength of the corresponding functional connectivity. These results provide a partial validation for using fMRI functional connectivity to assess brain interregional relations.
authors.affiliation: Brain Imaging and Modeling Section, National Institute on Deafness and Other Communications Disorders, National Institutes of Health, Building 10, Room 6C420, MSC 1591, Bethesda, MD 20892, USA. horowitz@helix.nih.gov
authors.forename: Barry
authors.initials: B
authors.lastname: Horwitz
authors.forename: Brent
authors.initials: B
authors.lastname: Warner
authors.forename: Julie
authors.initials: J
authors.lastname: Fitzer
authors.forename: M-A
authors.initials: MA
authors.lastname: Tagamets
authors.forename: Fatima T
authors.initials: FT
authors.lastname: Husain
authors.forename: Theresa W
authors.initials: TW
authors.lastname: Long
mesh_terms: D001307:Auditory Perception / Q000502:physiology; D001345:Autoradiography; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D049268:Positron-Emission Tomography / Q000379:methods; D013569:Synapses / Q000502:physiology; D014796:Visual Perception / Q000502:physiology