September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
Changes in oscillatory brain activity around the time of saccades: an MEG study of voluntary horizontal saccades in near-darkness condition
Author Affiliations
  • David Acunzo
    Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
  • David Melcher
    Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
Journal of Vision August 2017, Vol.17, 897. doi:10.1167/17.10.897
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      David Acunzo, David Melcher; Changes in oscillatory brain activity around the time of saccades: an MEG study of voluntary horizontal saccades in near-darkness condition. Journal of Vision 2017;17(10):897. doi: 10.1167/17.10.897.

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Abstract

Peri-saccadic brain activity in humans has mainly been studied in the context of a perceptual task, making it difficult to disentangle activity related to the task, the visual transients, and saccade execution. To better characterize activity specific to eye movements, we tested participants in a dark room to limit visual transients and gave them no other task than to execute voluntary saccades between two horizontally-aligned and faint fixation points. Their brain activity was recorded with MEG while their eye movements were measured by the means of an eye-tracker and EOG electrodes. We found dramatic and consistent changes in oscillatory brain activity around the time of saccades. First, we observed an alpha power increase in parietal sensors as early as 500ms before saccade onset. This increase was most pronounced in sensors ipsilateral to the direction of the saccade, in a process possibly related to pre-saccadic changes in attention allocation. Second, there was a strong evoked response at fixation onset, likely due to re-afference of the visual signal. In addition, despite the weak visual input, we observed a long-lasting drop in power in a wide range of frequencies (7-40Hz) from 200ms following saccade execution, centered over parietal sensors but widespread over most posterior sensors. The alpha power drop was less pronounced for parietal sensors ipsilateral to the direction of the saccade. More generally, the pattern of oscillatory changes depended on the brain region, with large changes in oculomotor and visual cortical areas. These data indicate that, even with faint visual input, reliable power changes can be observed before and after saccade execution. These results are also useful in interpreting M/EEG studies that involve saccades.

Meeting abstract presented at VSS 2017

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