2013年7月25日木曜日

Restricting Temptations: Neural Mechanisms of Precommitment

Molly J. Crockett, Barbara R. Braams, Luke Clark, Philippe N. Tobler, Trevor W. Robbins, Tobias Kalenscher
Neuron, Volume 79, Issue 2, 391-401, 24 July 2013

ヒトfMRI:「誘惑に打ち勝つ」際の脳活動。
外側前頭極(LFPC)とその後ろに位置する背外側前頭前野(DLPFC)が協調することで「自制心」と「Precommitment(事前に、誘惑の元になる選択肢を選べないようにしておく、退路を断つ)」が発揮され、誘惑に打ち勝つ事ができる。

Humans can resist temptations by exerting willpower, the effortful inhibition of impulses. But willpower can be disrupted by emotions and depleted over time. Luckily, humans can deploy alternative self-control strategies like precommitment, the voluntary restriction of access to temptations. Here, we examined the neural mechanisms of willpower and precommitment using fMRI. Behaviorally, precommitment facilitated choices for large delayed rewards, relative to willpower, especially in more impulsive individuals. While willpower was associated with activation in dorsolateral prefrontal cortex (DLPFC), posterior parietal cortex (PPC), and inferior frontal gyrus, precommitment engaged lateral frontopolar cortex (LFPC). During precommitment, LFPC showed increased functional connectivity with DLPFC and PPC, especially in more impulsive individuals, and the relationship between impulsivity and LFPC connectivity was mediated by value-related activation in ventromedial PFC. Our findings support a hierarchical model of self-control in which LFPC orchestrates precommitment by controlling action plans in more caudal prefrontal regions as a function of expected value.

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