Rapid neurophysiological markers of target detection during free eye movements

KAMIENKOWSKI JE; ISON MJ; QUIAN QUIROGA R; SIGMAN M

Washington

Congreso; Annual Meeting of the Society for Neuroscience; 2011

Society for Neuroscience

We report the study of concurrent eye movements and electroencephalographic (EEG) recordings while, in a free viewing condition, subjects produced a sequence of fixations, searching for hidden targets in a crowded scene. We describe consistent EEG responses upon fixation to the target stimuli. These fixation-event related potentials (fERPs) mimicked the event-related responses in a replay experiment in which subjects kept fixation in the center of the screen and sequences of images were presented simulating the spatial and temporal patterns occurring around the fovea during free viewing. Similar responses were observed in a second control experiment where the appearance of stimuli was controlled by the experimenters and presented at the center of the screen, as typically done in fixed gaze studies. The most significant difference between free viewing and replay during fixation was an early (~150 ms) physiological marker of stimulus identity that was observed only during free viewing.