Visùal evoked responses in normal and psychiatric subjects

Abstract

Visual evoked potentials (VEPs) and the cortical recovery cycle were studied in forty-five normal subjects, fifteen paranoid schizophrenics, fifteen neurotic depressives and fifteen psychotically depressed patients. The normals were divided into 3 groups: young, adult and old. For evaluation of the recovery cycle the ratio R2/R1 of wave III amplitude was employed. A procedure based on the analysis of covariance was then used for a direct comparison of R2 in different groups. In normal subjects the VEP showed a progressive increase in amplitude and latency as the subjects became older. A global decrease in the amplitude of the VEP was observed in schizophrenic subjects. Patients with endogenous depression had an evoked response of larger amplitude. In neurotic depressed patients it was not possible to detect substantial differences from normal. The recovery cycle of normal subjects showed a progressive increase in the facilitation period with the progress of age. This facilitation period was very short and almost absent in the three groups of psychiatric patients. A comparison of R2 adjusted values showed important differences between neurotically depressed, schizophrenic and normal subjects. These data suggest that the psychiatric population has some defect in the facilitatory mechanisms.