TASK
- SPECIFIC PROCESSING OF STIMULI IN MONKEY POSTERIOR PARIETAL CORTEX
( PPC )
G.Stoet*; L.H.Snyder
We
studied neural correlates of task information and task-specific
stimulus processing in two macaque monkeys. Two discrimination tasks
were randomly interleaved. Depending on the task, animals judged
either stimulus color (red or green) or orientation (horizontal or
vertical). Trials started with a 250 ms visual task instruction.
After a 450 ms preparation interval, a colored, oriented target
appeared. Animals pressed one of two buttons to indicate their
judgment. We defined a task-specific information processing cell
as one that encodes task information, in which the task encoding
persists after the target appears, and in which the neural responses
to identical targets depend on the task being performed and the
cell's task preference. To determine whether cells in PPC encode
task information, we compared activity during the last 250 ms of the
preparation interval following different task instructions (376
neurons). In the lateral bank of the IPS (IPS-L), the firing of 17%
of neurons depended on which task was instructed, regardless of the
instruction format (P<.01). Across this population of IPS-L
task-selective cells, task effects persisted even after the target
was presented (150-350 ms after target presentation, paired t-test,
P<0.05). Finally, the response to identical targets was larger
during performance of the preferred task compared to the
non-preferred task (150-350 ms after target presentation, paired
t-test, P<0.01). Effects were similar in both animals. These
data indicate that IPS-L cells encode task information, and suggest
that task-encoding cells are involved in the task-specific
processing of visual information.
Citation: G.Stoet,
L.H.Snyder. TASK - SPECIFIC PROCESSING OF STIMULI IN MONKEY POSTERIOR
PARIETAL CORTEX ( PPC ) Program No. 559.13. 2002 Abstract
Viewer/Itinerary Planner. Washington, DC: Society for
Neuroscience, 2002. CD-ROM.