Neurophysiological evidence of corollary discharge dysfunction in schizophrenia.

Objective: Speaking is hypothesized to generate a corollary discharge of motor speech commands transmitted to the auditory cortex, dampening its response to self-generated speech sounds. Event-related potentials were used to test whether failures of corollary discharge during speech contribute to the pathophysiology of schizophrenia.

Method: The N1 component of the event-related potential elicited by vowels was recorded while the vowels were spoken by seven patients with schizophrenia and seven healthy comparison subjects and while the same vowels were played back.

Cortical responsiveness during inner speech in schizophrenia: an event-related potential study.

Objective: The study assessed the effects of inner speech on auditory cortical responsiveness in schizophrenia.

Method: Comparison subjects (N=15) and patients with schizophrenia (N=15) were presented with acoustic and visual stimuli during three conditions: while subjects were silent, when spontaneous inner speech might occur; during directed inner speech, while subjects repeated a statement silently to themselves; and while subjects listened to recorded speech. N1 event-related potentials were recorded during the three conditions.

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).

N1 and P300 abnormalities in patients with schizophrenia, epilepsy, and epilepsy with schizophrenialike features.

Background: The scalp-recorded N1 and P300 components of the event-related brain potential (ERP) are commonly reduced in patients with schizophrenia but not in patients with epilepsy. Epilepsy patients with interictal chronic schizophrenialike features (EPI-SZ) provide a comparison group for determining whether the ERP amplitude abnormalities seen in schizophrenic patients are associated with shared clinical features of EPI-SZ and schizophrenic patients or overlapping pathophysiologies, or are specific to a distinct schizophrenia etiology.

Methods: Patients with schizophrenia (n = 24) were compared with normal control subjects (n = 32) and patients with epilepsy syndromes on visual and auditory oddball ERP paradigms.