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Abstract:
Abstract: We recorded isolated neurons in the superior
colliculus (SC) while monkeys performed a task in which they made
saccades to odd-colored targets presented among distractors. We
compared responses in this task with responses for saccades made to
single stimuli. For saccades to single stimuli, SC visuomotor burst
neurons produce two discrete bursts of activity: an initial
response to the visual target, followed by a burst occurring near
saccade onset. Surprisingly, in our search task, these neurons
showed three discrete bursts of activity: the initial visual
response was followed by a second discrete burst of activity
followed, finally, by a third burst occurring around the time of
saccade initiation. The second burst was significantly higher when
the target, rather than a distractor, was present in the response
field. A different subgroup of neurons showed a more gradual and
steady build-up of activity before saccade onset. This activity
began to distinguish the target and distractor stimuli at around
the same time as the occurrence of the second burst of activity in
the visuomotor burst neurons. Finally, we identified a third
subgroup of burst neurons lacking a visual response, which did not
show significant activity distinguishing the target from the
distractors until immediately before saccade onset. These results
provide insight into the flow of information related to target
selection in the SC.
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