2012年4月19日木曜日

Learning and Generalization under Ambiguity: An fMRI Study


J R Chumbley, G Flandin, D R Bach, J Daunizeau, E Fehr, R J Dolan, and K J Friston
PLoS Comput Biol, 2012 vol. 8 (1) p. e1002346

「般化(過去の学習結果を新しい状況に応用する)」のfMRI研究。実験では「般化可能な状況」と「不可能な状況」が交互に出てくる。被験者は「(どの程度)般化できるのか否か」をベイズ的に学習。また、その「程度」は海馬に保持されている。 http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1002346

Adaptive behavior often exploits generalizations from past experience by applying them judiciously in new situations. This requires a means of quantifying the relative importance of prior experience and current information, so they can be balanced optimally. In this study, we ask whether the brain generalizes in an optimal way. Specifically, we used Bayesian learning theory and fMRI to test whether neuronal responses reflect context-sensitive changes in ambiguity or uncertainty about experience-dependent beliefs. We found that the hippocampus expresses clear ambiguity-dependent responses that are associated with an augmented rate of learning. These findings suggest candidate neuronal systems that may be involved in aberrations of generalization, such as over-confidence.

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