Abstract
Eye movements are a pervasive element of our everyday interactions with the environment and can be systematically planned (voluntary) or in response to the abrupt onset of a stimulus (reactive). While voluntary and reactive saccades have been linked to different cortical pathways, many questions remain about their constituent networks. In this study we sought to identify the neural activity associated with reactive saccades by using synchronized EEG and eye tracking measures. Here, participants conducted a free-viewing visual search over a distribution of static Gabor stimuli in order to identify, via button press, the vertically oriented targets. During the search, transient Gabor stimuli were also presented, requiring an immediate saccade in order to assess orientation before stimulus extinction. In our analysis, we separated these reactive saccades into quartiles based on the time between stimulus presentation and saccade onset (i.e. saccade reaction time, SRT). The corresponding stimulus and saccade-locked event-related potentials were then estimated using both standard averaging and regression-based techniques. We found that the amplitude of the late positive potential, evoked by transient stimuli, exhibited a significant inverse relationship with SRT. This phenomenon persisted even when accounting for the effects of Gabor spatial frequency, saccade magnitude, and EEG activity related to ocular muscle artifacts. Our results suggest that the late positive potential, commonly associated with attentional capture, may also index the onset of reactive saccades.
Meeting abstract presented at VSS 2018