2013年10月6日日曜日

Online evaluation of novel choices by simultaneous representation of multiple memories

Helen C Barron, Raymond J Dolan & Timothy E J Behrens
Published online: 08 September 2013 | doi:10.1038/nn.3515

ヒトfMRI。
脳は「新しい(経験したことのない)選択肢の価値」をどう評価しているのか?
fMRI adaptation(「同じ種類の刺激を続けて呈示すると、その刺激を処理する脳部位のfMRI信号が低下する」現象)を用いて検証。
→ 海馬(Hippocampus)、前頭前野内側部(mPFC)から「(過去に経験済みの)選択肢の価値」を読み出し、それらを組み合わせて「新しい選択肢の価値」を計算している。

Prior experience is critical for decision-making. It enables explicit representation of potential outcomes and provides training to valuation mechanisms. However, we can also make choices in the absence of prior experience by merely imagining the consequences of a new experience. Using functional magnetic resonance imaging repetition suppression in humans, we examined how neuronal representations of novel rewards can be constructed and evaluated. A likely novel experience was constructed by invoking multiple independent memories in hippocampus and medial prefrontal cortex. This construction persisted for only a short time period, during which new associations were observed between the memories for component items. Together, these findings suggest that, in the absence of direct experience, coactivation of multiple relevant memories can provide a training signal to the valuation system that allows the consequences of new experiences to be imagined and acted on.

0 件のコメント:

コメントを投稿