2012年6月6日水曜日

Action Selection and Action Value in Frontal-Striatal Circuits


Moonsang Seo, Eunjeong Lee, Bruno B. Averbeck
Neuron, Volume 74, Issue 5, 947-960, 7 June 2012

サル電気生理。前頭前野と線条体はどちらも「行動の価値」や「行動選択」に関係すると言われていたが、実は、行動価値は主に(背側)線条体にコードされ、行動選択は主に(外側)前頭前野で行われている。

The role that frontal-striatal circuits play in normal behavior remains unclear. Two of the leading hypotheses suggest that these circuits are important for action selection or reinforcement learning. To examine these hypotheses, we carried out an experiment in which monkeys had to select actions in two different task conditions. In the first (random) condition, actions were selected on the basis of perceptual inference. In the second (fixed) condition, the animals used reinforcement from previous trials to select actions. Examination of neural activity showed that the representation of the selected action was stronger in lateral prefrontal cortex (lPFC), and occurred earlier in the lPFC than it did in the dorsal striatum (dSTR). In contrast to this, the representation of action values, in both the random and fixed conditions, was stronger in the dSTR. Thus, the dSTR contains an enriched representation of action value, but it followed frontal cortex in action selection.

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