Human EEG Potentials before Express Saccades

摘要

Using EEG backward averaging method there were fast negative and positive potentials found before regular short latency saccades and express-saccades. These potentials can reflect different stages of presaccadic preparation which include processes of saccadic system release of central fixation, attention disengagement from the central stimulus, decision making and activation of premotor cortical and subcortical structures. There were two schemes of visual stimulus presentation used -"step" and with a 200-ms "gap". Analysis of parameters and spatiotemporal dynamics of potentials allowed us to assume that express-saccades appear in conditions when the previously selected motor programm and prediction of the target location coincides with the real coordinates of the target. At that optimum preparation of neuronal structure and a high level of readiness and attention are necessary. Decreasing an express-saccade latency can be the result of participation of main oculomotor areas of motor and saccadic planning in express-saccades initiation, particularly by direct signal transferring from the cortex to the saccadic brainstem generator, by-passing superior colliculus. Moreover, to successfully start initiation process and generate express-saccades, release from central fixation and attention disengagement has to begin in advance.