2012年5月8日火曜日

Action controls dopaminergic enhancement of reward representations


Marc Guitart-Masip, Rumana Chowdhury, Tali Sharot, Peter Dayan, Emrah Duzel, and Raymond J. Dolan
PNAS May 8, 2012 vol. 109 no. 19 7511-7516

Dopamine is widely observed to signal anticipation of future rewards and thus thought to be a key contributor to affectively charged decision making. However, the experiments supporting this view have not dissociated rewards from the actions that lead to, or are occasioned by, them. Here, we manipulated dopamine pharmacologically and examined the effect on a task that explicitly dissociates action and reward value. We show that dopamine enhanced the neural representation of rewarding actions, without significantly affecting the representation of reward value as such. Thus, increasing dopamine levels with levodopa selectively boosted striatal and substantia nigra/ventral tegmental representations associated with actions leading to reward, but not with actions leading to the avoidance of punishment. These findings highlight a key role for dopamine in the generation of appetitively motivated actions.

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