An investigation of the human cortical evoked potential under conditions of monaural and binaural stimulation.

The human cortical potential evoked by a 1000-Hz tone was recorded under conditions of binaural and monaural stimulation which covered a wide range of stimulus intensities. The results showed that (1) the curve for the amplitude as well as for the area confined by the potential increased with increases in stimulus intensity. At higher stimulus intensities, these curves leveled off. (2) Bilateral stimulation generated larger cortical potentials than did monaural stimulation. (3) Latency of the potential decreased with increases in stimulus intensity. When the monaural stimulus was delivered to the ear contralateral to the active scalp electrode, the various components of the potential showed consistently a shorter latency than when the monaural stimulus was presented ipsi-laterally.This research was supported by a grant from the National Institute of Neurological Diseases and Blindness, USA., and the Deutsche Forschungsgemeinschaft.