Think differently: a brain orienting response to task novelty.
Cognitive flexibility hinges on a readiness to direct attention to novel events, and on an ability to change one's mental set to find new solutions for old problems. Human event-related potential (ERP) studies have described a brain 'orienting' response to discrete novel events, marked by a frontally distributed positive potential peaking 300-400 ms post-stimulus (P3a). This brain potential has been typically related to bottom-up processing of novel non-targets under a fixed task-set (i.e., press a button to coloured targets), but had never been related to top-down attention control in dual-task paradigms. In this study, 27 subjects had their ERPs measured while they performed a version of the Wisconsin card sorting test (WCST), a dual-task paradigm where the same feedback cue signalled unpredictable shifts to a new task set (i.e., from 'sort by colour' to 'sort by shape'). Feedback cues that directed a shift in the subject's mental set to a new task-set elicited frontally distributed P3a activity, thus suggesting a role of the P3a response system in task-set shifting. Feedback cues also evoked a longer latency positive potential (350-600 ms; P3b), that was larger the more task rules were held in memory. In line with current models of prefrontal function in the executive control of attention, this P3a/P3b response system appears to reflect the co-ordinated action of prefrontal and posterior association cortices during the switching and updating of task sets in working memory.
Barceló
Francisco
F
Department of Psychology, University of Balearic Islands, Palma de Mallorca. f.barcelo@uib.es
Periáñez
José A
JA
Knight
Robert T
RT
D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003463:Cues; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008959:Models, Neurological; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology