The attentional disengagement processing reflected by ERPs and saccade reaction times during a gap task

Abstract

In this study, we examined cerebral process of attentional disengagement using ERPs and saccade reaction time (SRT) during a saccadic eye movement task to produce the gap effect. Ten healthy adults participated in this study. Subjects were required to execute saccadic eye movement when the target appeared. In the gap condition, a fixation point disappeared 200 ms prior to the target stimulus presentation. In the overlap condition, a fixation point remained after the target stimulus presentation. ERPs were analyzed separately for target stimulus and saccadic eye movement. SRT in the gap condition was significantly shorter than that in the overlap condition. For the target-locked ERPs in the gap condition, central positivity appeared around 60 ms before the onset of the target stimulus. This would reflect an automatic processing of attentional disengagement elicited by the offset of a fixation point. For the saccade-locked ERPs, pre-saccadic positivities were observed in both conditions. In the overlap condition, it appeared earlier and higher than that in the gap condition. It reflects a processing of attentional disengagement to the fixation point. These results indicated that the cerebral processing of attentional disengagement would be differentiated by the existence of gap.