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Abstract:
SEF neurons fire during planned saccades to remembered visual
stimuli. This activity might reflect involvement of the SEF in
oculomotor programming or spatial memory. To distinguish between
these possibilities, we monitored neuronal activity in the SEF
while monkeys performed three tasks. (1) Memory guided saccade. A
brief peripheral cue instructed the monkey where to make a saccade
at the trial's end. This task required oculomotor programming and
spatial memory. (2) Delayed saccade. A continuous peripheral cue
served as target for a saccade executed at trial's end. This task
required oculomotor programming only. (3) Delayed match to sample.
The monkey released a lever when a probe appeared at a remembered
location. This task required spatial memory only. Two findings
emerged. (a) Activity encoding location of the cue was stronger
during the delayed match to sample task than during the oculomotor
task. This suggests that directional signals in the SEF are related
to the memory of a spatial locus at least as much as they are to
programming of eye movements. (b) Neurons active in oculomotor
tasks fell into two populations, each more active during either
memory or visually guided saccades. These findings imply that the
SEF is involved in spatial working memory as distinct from saccade
programming. Supported by: NIH EY11831
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