A LEFT TEMPORAL-LOBE IMPAIRMENT OF AUDITORY INFORMATION-PROCESSING INSCHIZOPHRENIA - AN EVENT-RELATED POTENTIAL STUDY

A measure of auditory prepulse inhibition (PPI) is the reduction of th e scalp-recorded P1 event-related potential (ERP) after a sound that i s preceded by 100-300 ms by a click as prepulse. This measure of senso ry gating was adapted to study the effect of a prepulse on processing tones that were part of a 'go no-go' discrimination. ERPs were recorde d at right and left, frontal and temporal sites in groups of patients with schizophrenia (SCH) or obsessive compulsive disorder (OCD) and he althy controls (CON). A prepulse 100 ms but not 500 ms before either t one reduced the Fl ERP amplitude in healthy and OCD subjects but not S CH patients. At frontal and temporal recording sites the Fl amplitude was similar bilaterally in controls but showed a right temporal shift in the SCH patients. If the tone was the 'no-go' tone, the prepulse re duced the N1 amplitude in both the CON and SCH groups. The N1 was simi lar, bilaterally in controls but again showed a right temporal shift i n the SCH group. These results show a reduction of a PPI-like effect o n early processing (Pi) that is more marked in the left hemisphere of SCH patients and may affect channel selection for processing informati on (N1) about task-relevant sounds. (C) 1997 Elsevier Science Ireland Ltd.