title: Fractionating the neural substrate of cognitive control processes.
abstract: Psychological and neurobiological theories of cognitive control must account for flexible, seemless transitions among cognitive operations. When subjects switch between tasks, they must both inhibit the previous task and re-engage in a different task. Inhibition of the disengaged task remains active for a period of time and has to be overcome when re-engaging in the same task. Here we used a task-switching paradigm that allows distinction of two control processes: overcoming the inhibition of a previously performed task when re-engaging it and restarting a sequence of tasks after a period of interruption. Behaviorally, these processes were reflected in the facts that: (i) switching to a recently performed task, that is thus unlikely to have fully recovered from inhibition, takes longer than switching to a task less recently performed and (ii) re-engaging in a sequence of tasks after a period of interruption transiently increases response time. Using event-related functional MRI, we found that these two behavioral effects were accompanied by a double dissociation: the right lateral prefrontal cortex was more activated when switching to a task recently performed compared to a task less recently performed, while the anterior cingulate cortex was recruited when a sequence of tasks was initiated. These results provide insights into the functional organization of the frontal lobe in humans and its role in distinct processes involved in cognitive control.
authors.affiliation: Unit on Integrative Neuroimaging, Clinical Brain Disorders Branch, National Institute of Mental Health, National Institutes of Health, Intramural Research Program, Bethesda, MD 20892-1365, USA. dreherj@intra.nimh.nih.gov
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dreher
authors.forename: Karen Faith
authors.initials: KF
authors.lastname: Berman
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009474:Neurons / Q000502:physiology; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000502:physiology; D011859:Radiography; D011930:Reaction Time; D013647:Task Performance and Analysis