言語種別	日本語
発表タイトル	Reward coding by the primate dorsal raphe neurons is context dependent.
会議名	第32回　日本神経科学学会
学会区分	全国規模の学会
発表形式	ポスター掲示
講演区分	一般
発表者・共同発表者	◎Nakao K, Matsuzaki R, Okada O, Kobayashi Y, Nakamura K
発表年月日	2009/09
開催地 （都市, 国名）	名古屋
概要	We have previously shown that the activity of neurons in the dorsal raphé nucleus (DRN), a major source of serotonin, is modulated by the received reward size. To study whether the DRN activity is involved in delay-based cost-benefit decision-making, we recorded single-neuronal activity in the DRN while a monkey performed a delayed-reward visually-guided saccade task. In the task, reward value (0.01 vs. 0.5ml) was indicated by the location of saccade target (right vs. left), and after saccade, a reward was delivered with a 1600ms delay. We found that about half (23/45) of DRN neurons exhibited sustained activity during the delay period 'after' saccade and before reward delivery, with either large- or small-reward preference. The same neurons often showed significantly less reward modulation if the delay (1600ms) was introduced 'before' saccade in a memory-guided saccade task. These results suggest that the coding of the size of delayed reward is dependent on the task context such as the sequence in a task.