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Abstract:
To reveal the roles of primate orbitofrontal cortex (OFC) in
rapid change of behavior based on visual discrimination, we
recorded single neuronal activity from the OFC of a macaque monkey
while performing a visual conditional GO/NO-GO task with motor and
reward reversal. While the monkey was gazing a fixation point on a
CRT display and holding a joy stick by his hand, one of a pair of
visual cues was presented for 0.6 s. When the fixation point was
dimmed after a following delay, the monkey was required to choose
GO or NO-GO motor responses depending on the cue to get reward
asymmetrically associated with one of the cues. After complete
learning a combination of the visual-motor-reward association, the
visual-motor or visual-reward association was reversed to learn
again. On the early stage of the training, the performance was
lowered after the visual-reward as well as the visual-motor
reversal. Many OFC neurons showed different responses to the visual
cues. Most of these responses rapidly changed to follow the reward
contingency rather than motor one across the reversals. These
results suggest that the OFC might contribute to flexible change of
visually cognitive behavior by rapid change in activity with
reversal not in visual-motor but in visual-reward
association.
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