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Abstract:
Abstract: Neurons of the macaque supplementary eye field
(SEF) are active during the delay period of an oculomotor delayed
response (ODR) task, firing at a rate that depends both on the
direction of the impending response and on the nature of the
instructional cue presented at the beginning of the trial. Many
neurons are more active following a 'pattern' cue (a digitized
image arbitrarily associated with the response direction) than
following a 'spatial' cue (a white spot flashed at the location of
the target). While changes in mean firing rate are informative,
they are not an exhaustive measure of a neuron's activity. The aim
of the present study was to develop a method for analyzing
task-dependent changes in the temporal profile of delay-period
activity. We analyzed data from 84 neurons from a monkey trained to
perform a variant of ODR in which, on interleaved trials, the
response might be in any of four directions, and the direction
might be indicated by either a 'pattern' or a 'spatial' cue. To
determine whether there was an effect of task on profile
characteristics, such as the time at which maximal firing rate
occurred, we used Poisson nonparametric regression and bootstrap
methods. This approach revealed clear task-dependent variations in
the temporal profile of individual neurons' delay-period activity.
Neuronal activity peaked later under 'pattern' than under 'spatial'
conditions.
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