Is the prefrontal cortex necessary for establishing cognitive sets?
There is evidence from neuroimaging that the prefrontal cortex may be involved in establishing task set activity in advance of presentation of the task itself. To find out whether it plays an essential role, we examined patients with unilateral lesions of the rostral prefrontal cortex. They were first instructed as to whether to perform a spatial or a verbal working memory task and then given spatial and verbal items after a delay of 4-12 s. The patients showed an increase in switch costs, making more errors by repeating what they had done on the previous trial. They were able to establish regional task set activity during the instruction delay, as evidenced by sustained changes in the blood oxygenation level-dependent signal in caudal frontal regions. However, in contrast to healthy controls, they were less able to maintain functional connectivity among the surviving task-related brain regions, as evidenced by reduced correlations between them during instruction delays. The results suggest that the left rostral prefrontal cortex is indeed required for establishing a cognitive set but that the essential function is to support the functional connectivity among the task-related regions.
Department of Clinical Neurosciences, Cambridge University, Cambridge CB2 2QQ, United Kingdom. james.rowe@mrc-cbu.cam.ac.uk
James B
JB
Rowe
Katsuyuki
K
Sakai
Torben E
TE
Lund
Thomas
T
Ramsøy
Mark Schram
MS
Christensen
William F C
WF
Baare
Olaf B
OB
Paulson
Richard E
RE
Passingham
D000328:Adult; D000704:Analysis of Variance; D001930:Brain Injuries / Q000473:pathology* / Q000503:physiopathology; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D017397:Prefrontal Cortex / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D012718:Set, Psychology
D010100:Oxygen