2014年1月5日日曜日

Fear Learning Enhances Neural Responses to Threat-Predictive Sensory Stimuli

Marley D. Kass, Michelle C. Rosenthal, Joseph Pottackal, John P. McGann
Science 13 December 2013: Vol. 342 no. 6164 pp. 1389-1392

恐怖条件づけ:マウスに「特定の匂い刺激」と「電気ショック」の連合を学習させる。
匂い知覚系の最初に位置する神経細胞(鼻腔で匂い分子を感知してその情報を脳内の嗅球に送る)からの出力の段階で、電気ショックに関連付けられた刺激とその他の刺激を区別している。
つまり、恐怖などの情動情報は神経システムの初期段階(刺激入力の直後)ですでにコードされている。

The central nervous system rapidly learns that particular stimuli predict imminent danger. This learning is thought to involve associations between neutral and harmful stimuli in cortical and limbic brain regions, though associative neuroplasticity in sensory structures is increasingly appreciated. We observed the synaptic output of olfactory sensory neurons (OSNs) in individual mice before and after they learned that a particular odor indicated an impending foot shock. OSNs are the first cells in the olfactory system, physically contacting the odor molecules in the nose and projecting their axons to the brain’s olfactory bulb. OSN output evoked by the shock-predictive odor was selectively facilitated after fear conditioning. These results indicate that affective information about a stimulus can be encoded in its very earliest representation in the nervous system.

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