Cortical responsiveness during talking and listening in schizophrenia: an event-related brain potential study.
BACKGROUND
Failures to recognize inner speech as self-generated may underlie positive symptoms of schizophrenia-like auditory hallucinations. This could result from a faulty comparison in auditory cortex between speech-related corollary discharge and reafferent discharges from thinking or speaking, with misattribution of internal thoughts to external sources. Although compelling, failures to monitor covert speech (thoughts) are not as amenable to investigation as failures to monitor overt speech (talking).


METHODS
Effects of talking on auditory cortex responsiveness were assessed in 10 healthy adults and 12 patients with schizophrenia (DSM-IV) using N1 event-related potentials (ERPs) to acoustic and visual probes during talking aloud, listening to one's speech played back, and silent baseline. Trials contaminated by muscle artifact while talking were excluded.


RESULTS
Talking and listening affected N1 to acoustic but not to visual probes, reflecting modality specificity of effects. Patterns of responses to acoustic probes differed between control subjects and patients. N1 to acoustic probes was reduced during talking compared with baseline in control subjects, but not in patients. Listening reduced N1 equivalently in both groups.


CONCLUSIONS
Although the failure of N1 to be reduced during talking was not related to current hallucinations in patients, it may be related to the potential to hallucinate.
Ford
J M
JM
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305-5550, USA.
Mathalon
D H
DH
Kalba
S
S
Whitfield
S
S
Faustman
W O
WO
Roth
W T
WT
D000328:Adult; D000704:Analysis of Variance; D001303:Auditory Cortex; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013067:Speech Perception