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Abstract:
Abstract: Previous research has identified a negative
component of event-related brain potentials (ERPs) time-locked to
error responses in forced choice reaction time tasks known as the
error-related negativity (ERN; Gehring et al, 1995), thought to
reflect an error monitoring system in the brain. Many symptoms of
schizophrenia (e.g., hallucinations, delusions) are characterized
by difficulties distinguishing internally and externally generated
experiences, perhaps due to deficits in self monitoring. Error
monitoring, a type of self monitoring, was assessed using the ERN
in 18 schizophrenic patients and 18 age- and sex-matched controls.
ERPs were recorded during a picture-word matching task in which
subjects pressed a response key with one hand for matches and the
other for nonmatches. Response synchronized ERPs were separately
averaged to correct and incorrect responses. In controls, errors
elicited a large midline fronto/central ERN peaking at around 100
msec after the response, while correct trials showed no such
negativity centrally and a small negative peak frontally
(correct-related negativity, CRN). Patients showed a reduced ERN
relative to controls, but also showed a large CRN comparable in
amplitude to their ERN. At an early stage of response monitoring,
ERPs from patients do not distinguish between correct and incorrect
responses, a dysfunction that may contribute to the positive
symptoms of schizophrenia. NIMH (MH40052, MH58262), DVA.
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