Evoked potentials of schizophrenics in several sensory modalities.

This is the initial report of results obtained by a comprehensive approach to investigation of evoked potential (EP) characteristics of psychiatric patients. EP to left and right medion nerve, visual (checkerboard flash), and auditory (click) stimuli were obtained for 14 monopolar scalp and one EOG derivation in 32 schizophrenics and 16 nonpatients, matched for age and sex. Results showed amplitude attenuation of EP events 100 msec poststimulus or later in the patients' EPs of all modalities and in most lead locations. Attenuation of later EP events thus appears to be a general characteristic of schizophrenia. Comparisons of chronic paranoid and undifferentiated with other patient subtypes revealed a relatively specific correlate of the chronic subgroup, increased negativity of a negative somatosensory peak occurring 60 msec poststimulus (N60) at contralateral central leads.