Parietal dysfunction is associated with increased outcome-related decision-making in schizophrenia patients.
BACKGROUND
Decision-making is a complex process and depends on a network of fronto-parietal and cingulate areas. Decision-making dysfunctions in schizophrenia patients are characterized by an alternation between stereotypic and unpredictable responses. This study tested the hypothesis that schizophrenia patients show less decision-making-related activation in the prefrontal and parietal cortex.


METHODS
Fifteen schizophrenia patients were matched with fifteen normal comparison subjects. During functional magnetic resonance imaging (fMRI) scanning, subjects were tested on the two-choice prediction task (predicting the location of a randomly presented stimulus) and the two-choice response task (responding according to the location of the stimulus).


RESULTS
Schizophrenia patients relative to comparison subjects generated more outcome-dependent responses. Schizophrenia patients and normal comparison subjects showed decision-making-related activation in right prefrontal cortex, insula, anterior cingulate, and bilateral precuneus. Schizophrenia patients showed less activation in inferior, medial prefrontal, and right superior temporal cortex and more activation in the postcentral and inferior parietal cortex. Decision-making-related activation in both right prefrontal and bilateral parietal cortex was higher in medicated compared to unmedicated schizophrenia patients.


CONCLUSIONS
These results support the hypothesis that the interaction between prefrontal and parietal cortex during decision-making by schizophrenia patients is dysregulated, which results in an increased outcome-dependent response selection.
Paulus
Martin P
MP
Department of Psychiatry, University of California San Diego, La Jolla, California 92093-0603, USA.
Hozack
Nikki E
NE
Zauscher
Blanca E
BE
Frank
Lawrence
L
Brown
Gregory G
GG
McDowell
Jennifer
J
Braff
David L
DL
D000328:Adult; D001931:Brain Mapping; D003657:Decision Making; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010296:Parietal Lobe / Q000503:physiopathology*; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013647:Task Performance and Analysis