Abstract
Experiments evaluating the relationship between sensory and oculomotor systems have utilized a variety of methods to evaluate the extent to which these systems are interrelated, how they interact, and the mechanisms that influence them. Results from psychophysics, microstimulation, and electrophysiology all suggest an enhancement of sensory processing when the oculomotor system is activated – that is, prior to the onset of a saccade, visual discrimination performance is improved at the saccade endpoint (Rolfs & Carrasco, 2012), and electrophysiological responses measured from individual neurons (Moore et al, 1998) and the scalp (Krebs et al, 2012) are enhanced. However, disentangling population-level signals related to top-down control/motor preparation and those purely related to sensory processing is often challenging. To address this issue, we measured steady-state visual evoked potentials (SSVEP) using electroencephalography (EEG) prior to the onset of voluntary saccades towards flickering stimuli in the left and right visual fields. On each trial, observers were presented with an endogenous cue at fixation, instructing them to saccade towards a corresponding flickering checkerboard stimulus or maintain fixation. We observed an increase in SSVEP power evoked by the saccade target just prior to saccade onset compared to SSVEPs during fixation trials in which the eyes did not move. This work reinforces the utility of the SSVEP technique in isolating sensory responses during an oculomotor task, and suggests that sensory-driven signals can be enhanced prior to oculomotor execution.
Meeting abstract presented at VSS 2014