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Why there is no top-down inhibition of specific saccades| old_uid | 11945 |
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| title | Why there is no top-down inhibition of specific saccades |
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| start_date | 2012/12/14 |
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| schedule | 11h-12h |
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| online | no |
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| summary | Saccade trajectories are rarely straight, and irrelevant distractors can make them deviate towards their location, or away from it. The oculomotor mechanisms that produce deviation towards distractors have been thoroughly explored in behavioral, neurophysiological and computational studies. The mechanisms underlying deviation away, on the other hand, remain unclear. Behavioral findings suggest a mechanism of spatially focused, top-down inhibition in a saccade map, and deviation away has become a tool to investigate such inhibition. However, this inhibition hypothesis has little neuroanatomical or neurophysiological support. Here, I will discuss a computational model of the saccade system that incorporates another hypothesis: That deviation away results from an unbalanced saccade drive from the brainstem, caused by spike rate adaptation in brainstem long-lead burst neurons. The model simulates a wide range of findings on saccade trajectories, including findings that have classically been interpreted to support inhibition views. Furthermore, the model predicts that saccade latency affects deviation away in some, but not other conditions. I will discuss an experiment that confirms this prediction, and another that suggests that inhibition of distractor features also does not exist. |
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| responsibles | Pélissier |
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