Defects in auditory sensory gating and their apparent compensation in relatives of schizophrenics

Auditory sensory processing is defective at several stages in schizophrenics, as revealed by electrophysiological recordings. The purpose of this study was to assess the relationship between two of these defects in schizophrenics and their relatives. One defect is illustrated by the failure to gate the P50 wave of the auditory evoked potential in the conditioning-testing paradigm. In this paradigm, paired clicks are presented to the subject. Normals suppress or gate the P50 response to the second or test click. Schizophrenics fail to suppress the test response. This defect has been related to schizophrenics' inability to filter out noise in their environment. A second defect is illustrated by schizophrenics' lower than normal N100 wave, which has been related to failure to attend to particular features of interest in the stimulus. The question addressed in this study was whether these two defects inevitably occur together. While they do occur together in schizophrenics, even in very good prognosis, mildly ill subjects, they do not occur together in the relatives of schizophrenics. The defect in the gating of P50 occurs in half these relatives, but N100 amplitudes are not diminished. Instead, relatives with abnormal P50 gating have N100 amplitudes which are larger than normal. One interpretation of the data is that the relatives with the sensory gating defect can compensate for that defect at a subsequent stage of information processing, as demonstrated by their large amplitude N100 wave, whereas schizophrenic patients cannot.