Binocular interaction of visually evoked cortical potentials (VEPs) elicited by dichoptic binocular stimulation

Abstract

Purpose: To determine the interaction of cortical potentials elicited by dichoptic stimulation of the dominant and fellow eyes at different frequencies.

Methods: A pair of programmed power supply units were used to drive a light emitting diode (LED) mounted in the right and left eyes of light-proof goggles to elicit the VECPs. The right eye was stimulated at 11.5 Hz and the left eye at 11.0 Hz. The stimulus duration was 5 ms. The duration of collection was 200 ms and about 200 responses were averaged. The visually evoked cortical potential (VEP) of each eye was extracted separately. The components of the VEPs following monocular or binocular stimuli of the two eyes were compared.

Results: Individual VEPs could be recorded separately after simultaneous dichoptic stimulation of each eye. The amplitudes of the VEPs were not significantly different after stimulating the dominant eye and the fellow eye separately. The implicit times of N-2 and P-2 were shorter after stimulation of the dominant eye than after stimulation of the fellow eye but the difference was not significant. However, the implicit time of N-2 elicited by stimulating the dominant eye was significantly shorter when the stimulation rate was 11.5 Hz.

Conclusions: The VEPs elicited by stimulating the two eyes can be separately recorded with simultaneous dichoptic stimulation. Dichoptic simultaneous stimulation required a shorter time and may be a more sensitive method of analyzing binocular interactions compared to the classic VEPs using monocular stimulation.

Keywords: 433 bacterial disease • 507 electrophysiology: clinical • 755 visual cortex