2012年11月21日水曜日

Orbitofrontal Cortex Supports Behavior and Learning Using Inferred But Not Cached Values


Joshua L. Jones, Guillem R. Esber, Michael A. McDannald, Aaron J. Gruber, Alex Hernandez, Aaron Mirenzi, Geoffrey Schoenbaum
Science 16 November 2012: Vol. 338 no. 6109 pp. 953-956

OFCは「自身の報酬経験から直接的に学習された価値(model-free、cached)」ではなく「推論に基づく価値(model-based、inferred)」の処理に関わっている。

「刺激A→B、C→D」を学習後、「B→報酬、D→無報酬」を学習。OFCの活動を抑制されたラットは「B、D対呈示」ではBに反応するが、「A、C対呈示」ではどちらにも反応せず(健常なラットはAに反応)。OFCは「推論に基づく価値」処理に関係。 http://www.sciencemag.org/content/338/6109/953

Computational and learning theory models propose that behavioral control reflects value that is both cached (computed and stored during previous experience) and inferred (estimated on the fly on the basis of knowledge of the causal structure of the environment). The latter is thought to depend on the orbitofrontal cortex. Yet some accounts propose that the orbitofrontal cortex contributes to behavior by signaling “economic” value, regardless of the associative basis of the information. We found that the orbitofrontal cortex is critical for both value-based behavior and learning when value must be inferred but not when a cached value is sufficient. The orbitofrontal cortex is thus fundamental for accessing model-based representations of the environment to compute value rather than for signaling value per se.

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