2012年3月14日水曜日

Neuronal Encoding of Subjective Value in Dorsal and Ventral Anterior Cingulate Cortex


Xinying Cai and Camillo Padoa-Schioppa
J. Neurosci. 2012;32 3791-3808
http://www.jneurosci.org/cgi/content/abstract/32/11/3791?etoc

二種類のジュースから一つを選ぶ(サル電気生理)。前帯状皮質は「選ばれたジュース」の主観的価値をコードしている(一方、眼窩前頭皮質は「それぞれのジュースの価値」を保持)。前帯状皮質は意思決定過程の(運動制御に近い)下流に関与。 http://www.jneurosci.org/content/32/11/3791

We examined the activity of individual cells in the primate anterior cingulate cortex during an economic choice task. In the experiments, monkeys chose between different juices offered in variables amounts and subjective values were inferred from the animals' choices. We analyzed neuronal firing rates in relation to a large number of behaviorally relevant variables. We report three main results. First, there were robust differences between the dorsal bank (ACCd) and the ventral bank (ACCv) of the cingulate sulcus. Specifically, neurons in ACCd but not in ACCv were modulated by the movement direction. Furthermore, neurons in ACCd were most active before movement initiation, whereas neurons in ACCv were most active after juice delivery. Second, neurons in both areas encoded the identity and the subjective value of the juice chosen by the animal. In contrast, neither region encoded the value of individual offers. Third, the population of value-encoding neurons in both ACCd and ACCv underwent range adaptation. With respect to economic choice, it is interesting to compare these areas with the orbitofrontal cortex (OFC), previously examined. While neurons in OFC encoded both pre-decision and post-decision variables, neurons in ACCd and ACCv only encoded post-decision variables. Moreover, the encoding of the choice outcome (chosen value and chosen juice) in ACCd and ACCv trailed that found in OFC. These observations indicate that economic decisions (i.e., value comparisons) take place upstream of ACCd and ACCv. The coexistence of choice outcome and movement signals in ACCd suggests that this area constitutes a gateway through which the choice system informs motor systems.

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