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What the colliculus can and cannot do in saccade trajectory control

What the colliculus can and cannot do in saccade trajectory control. Ed Keller Smith-Kettlewell Eye Research Institute San Francisco, California. My collaborators. Kuniharu Arai Rob McPeek Koung-Min Lee. Population activity in the SC during saccades with variable trajectories

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What the colliculus can and cannot do in saccade trajectory control

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  1. What the colliculus can and cannot do in saccade trajectory control Ed Keller Smith-Kettlewell Eye Research Institute San Francisco, California

  2. My collaborators • Kuniharu Arai • Rob McPeek • Koung-Min Lee

  3. Population activity in the SC during saccades with variable trajectories • Use of a distributed model of the saccadic system to clarify trajectory control

  4. Types of variations in saccade trajectory produced by a visual search task

  5. Conclusion: if activity remains at two locations when a saccade starts, its trajectory curves toward the site of smaller activity A psychophysical observation in humans subjects: Saccade trajectory curves away from irrelevant visual stimuli (Doyle and Walker 2001) A hypothesis: active inhibition at the location of the irrelevant stimulus produces less activity at the SC site representing this location in visual Space (a hole instead of a mound?)

  6. Trajectories curve away from a lesion in the opposite field SC

  7. Parallel signal ` ` ` Parallel signal Parallel signal + +

  8. Population activity in the monkey superior colliculus during a 20-deg horizontal saccade (Anderson et al. 1998)

  9. Population activity in the monkey superior colliculus during a 20-deg horizontal saccade (Anderson et al. 1998)

  10. Population activity in the model SC for a simulated 20-deg saccade

  11. Population activity in the SC for two simultaneous visual stimuli, upper is the target

  12. Highly curved saccade with parallel inputs from the SC and the FN

  13. Conclutions • Completion between visual stimuli for the goal of a saccade can result in the presence of multiple loci of activity on the SC at saccade onset. • Saccade trajectory variation is associated with these loci of remaining activity. • In particular neural recordings and a distributed model of the saccadic system both indicate that directional errors at saccade onset, small curvature and end point averaging can be explained by dynamic changes in spatiotemporal activity in the SC. • Highly curved trajectories require the additional parallel corrective signals at the level of the saccadic burst generator.

  14. Distributed model of the saccadic system

  15. Population activity in the model SC when two identical visual stimuli are applied simultaneously Strong intracollicular lateral inhibition

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