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Viola Störmer, Patrick Cavanagh; Ipsilateral positivity as neurophysiological evidence for predictive remapping in humans. Journal of Vision 2016;16(12):100. doi: 10.1167/16.12.100.
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© ARVO (1962-2015); The Authors (2016-present)
Every time we move our eyes, the retinal image of the world shifts, but we nevertheless perceive the world as stable. Predictive remapping – a process in which neural activity elicited by a stimulus is transferred to its future, post-saccadic location before the execution of an eye movement – is thought to play a critical role in achieving this stability. Here, using EEG, we asked whether and at what point in time such remapping occurs during a simple saccade task. On each trial, participants fixated a black dot in the center of the screen that either turned red (as a cue to maintain fixation) or green (as a cue to execute a saccade to a pre-defined target location). 50 ms after the cue, a task-irrelevant visual stimulus (probe) was briefly flashed in the lower visual field halfway between the fixation and saccade target. We examined the event-related-potential (ERP) elicited by the probe prior to the execution of the saccade. During saccade preparation, the ERP waveforms showed an overall larger positivity over parietal-occipital cortex relative to when no saccade was prepared. However, this increase in neural activity was more pronounced over the hemisphere ipsilateral to the probe location – the hemisphere sensitive to the future retinal location of the probe. Surprisingly, this pre-saccadic ipsilateral positivity began only 50 ms after the probe (with the onset of the visual P1 component) and more than 120 ms before the execution of the saccade. These results are consistent with predictive remapping and suggest that during the preparation of an eye movement attention rapidly shifts to the post-saccadic stimulus location, thereby enhancing neural activity in the brain region responsible for the future stimulus location.
Meeting abstract presented at VSS 2016
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