Sensory processing related to vergence eye movements - an event-related potential study

Vergence eye movements, movements executed in opposite directions, have a crucial role in depth perception and are necessary for maintaining proper binocular vision. Despite these facts, the neurophysiological studies of vergence eye movement on humans are rare and give ambiguous results. In the present study, the sensory event-related potentials (ERPs) related to the processing of stimuli called for convergence, divergence and saccade were explored. Sixteen healthy subjects (mean 23 years old) performed reflexive (visually-guided) eye movements and event-related potentials from 64 active electrodes were recorded. The significant preponderance of cortical activity for convergence among three conditions was revealed and it concerned both anterior (larger negativity) and posterior cortex (larger positivity). Here, we also reported the longest latency for convergence. These results may suggest larger cortical representation for stimuli presented in near visual space, thus the preponderance of near cells within cortex, which respond to cross retinal image disparity being a cue for convergence.