Acquiring and inhibiting prepotent responses in schizophrenia: event-related brain potentials and functional magnetic resonance imaging.
BACKGROUND
Schizophrenia is associated with deficits in using context to establish prepotent responses in complex paradigms and failures to inhibit prepotent responses once established.


OBJECTIVE
To assess prepotent response establishment and inhibition in patients with schizophrenia using event-related brain potential (ERP) and functional magnetic resonance imaging (fMRI) in a simple NoGo task. To combine fMRI and ERP data to focus on fMRI activations associated with the brief (approximately 200 ms) moment of context updating reflected in the NoGo P300 ERP component.


METHODS
We collected ERP and fMRI data while subjects performed a NoGo task requiring a speedy button press to X stimuli (P=.88) but not to K stimuli (P=.12). The ERPs were collected at the Veterans Affairs Palo Alto Health Care System, Palo Alto, Calif; fMRIs were collected at Stanford University, Stanford, Calif.


METHODS
We recruited patients with DSM-IV schizophrenia (n=11) from the community and the VA hospital and sex- and age-matched healthy control subjects (n=11) from the community.


METHODS
Behavioral accuracy, P300 amplitudes and latencies, and fMRI activations suggested that patients with schizophrenia did not establish as strong a prepotent tendency to respond to the Go stimulus as healthy subjects. In healthy subjects, NoGo P300 was related to activations in the anterior cingulate cortex, dorsal lateral prefrontal cortex, and right inferior parietal lobule and caudate nucleus, perhaps reflecting conflict experienced when withholding a response, control needed to inhibit a response, and stopping a response in action, respectively. In patients with schizophrenia, NoGo P300 was modestly related to activations in the anterior cingulate cortex, which is consistent with experiencing conflict.


CONCLUSIONS
The difference in ERP and fMRI responses to Go and NoGo stimuli suggested that inhibiting a response was easier for patients with schizophrenia than for healthy subjects. Correlations of P300 and fMRI data suggested that patients with schizophrenia and healthy subjects used different neural structures to inhibit responses, with healthy subjects using a more complex system.
Ford
Judith M
JM
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif 94305-5550, USA. jford@stanford.edu
Gray
Max
M
Whitfield
Susan L
SL
Turken
And U
AU
Glover
Gary
G
Faustman
William O
WO
Mathalon
Daniel H
DH
D000328:Adult; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology / Q000502:physiology*; D003071:Cognition; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000503:physiopathology*; D013647:Task Performance and Analysis