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Arwen B. Long, Allison N. McCoy, Michael L. Platt; Posterior cingulate neurons encode visually and motivationally salient events. Journal of Vision 2006;6(6):741. doi: 10.1167/6.6.741.
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© ARVO (1962-2015); The Authors (2016-present)
In monkeys performing delayed saccade trials, posterior cingulate (CGp) neurons respond to visual target presentation, after saccade onset, and following reward delivery. These responses are modulated by expected reward size, probability, and variance. Furthermore, response strength predicts saccade accuracy. These results suggest the hypothesis that CGp neurons signal visuospatial salience, thus contributing to biased attention and orienting. This hypothesis predicts that CGp neurons should respond to salient visual cues in the absence of saccades and, further, that these responses should vary with cue reward value. To test this prediction, we recorded from single CGp neurons in monkeys performing a visual fixation task while peripheral cues were presented in the neuronal response field. Cue color predicted the size of reward delivered for correct performance and, across blocks, color-reward pairings were reversed. A population of CGp neurons showed sustained responses to visual cues and for some neurons these responses reflected cue value. One question these data raise is whether CGp neurons respond to salient events in the absence of any visuomotor task. To address this question, we delivered rewards at unpredictable intervals while monkeys sat passively in the dark. Many CGp neurons responded to reward delivery under these conditions. These results suggest that CGp neurons encode both visually and motivationally significant events.
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