2013年9月3日火曜日

Brain Activity in Valuation Regions while Thinking about the Future Predicts Individual Discount Rates

Nicole Cooper, Joseph W. Kable, B. Kyu Kim, and Gal Zauberman
J. Neurosci. 2013;33 13150-13156
http://www.jneurosci.org/cgi/content/abstract/33/32/13150?etoc

「未来のことを考えている」際の前頭前野腹内側部(vmPFC)及び腹側線条体(ventral striatum)の活動から、その被験者が「将来の報酬をどの程度割り引くのか」を予測できる。
報酬や意思決定とは必ずしも関係ない「未来のこと」という一般的な思考を行っている際の脳活動から「異時点間の報酬割引率」を予測できたのがポイント。

People vary widely in how much they discount delayed rewards, yet little is known about the sources of these differences. Here we demonstrate that neural activity in ventromedial prefrontal cortex (VMPFC) and ventral striatum (VS) when human subjects are asked to merely think about the future—specifically, to judge the subjective length of future time intervals—predicts delay discounting. High discounters showed lower activity for longer time delays, while low discounters showed the opposite pattern. Our results demonstrate that the correlation between VMPFC and VS activity and discounting occurs even in the absence of choices about future rewards, and does not depend on a person explicitly evaluating future outcomes or judging their self-relevance. This suggests a link between discounting and basic processes involved in thinking about the future, such as temporal perception. Our results also suggest that reducing impatience requires not suppression of VMPFC and VS activity altogether, but rather modulation of how these regions respond to the present versus the future.

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