2012年7月25日水曜日

Regionally Distinct Processing of Rewards and Punishments by the Primate Ventromedial Prefrontal Cortex


Ilya E. Monosov and Okihide Hikosaka
J. Neurosci. 2012;32 10318-10330
http://www.jneurosci.org/cgi/content/abstract/32/30/10318?etoc

彦坂研からvmPFC(前頭前野内腹側部)を対象としたサル電気生理。vmPFCの腹側/背側、後部/前部で、報酬に反応するのか、罰に反応するのか?報酬確率にphasicに反応するのか、tonicに反応するのか?がそれぞれ異なっている。

The ventromedial prefrontal cortex (vmPFC) is thought to be related to emotional experience and to the processing of stimulus and action values. However, little is known about how single vmPFC neurons process the prediction and reception of rewards and punishments. We recorded from monkey vmPFC neurons in an experimental situation with alternating blocks, one in which rewards were delivered and one in which punishments were delivered. Many vmPFC neurons changed their activity between blocks. Importantly, neurons in ventral vmPFC were persistently more active in the appetitive “reward” block, whereas neurons in dorsal vmPFC were persistently more active in the aversive “punishment” block. Furthermore, within ventral vmPFC, posterior neurons phasically encoded probability of reward, whereas anterior neurons tonically encoded possibility of reward. We found multiple distinct nonlinear valuation mechanisms within the primate prefrontal cortex. Our findings suggest that different subregions of vmPFC contribute differentially to the processing of valence. By conveying such multidimensional and nonlinear signals, the vmPFC may enable flexible control of decisions and emotions to adapt to complex environments.

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