2013年6月4日火曜日

A unified selection signal for attention and reward in primary visual cortex

Liviu Stănişor, Chris van der Togt, Cyriel M. A. Pennartz, and Pieter R. Roelfsema
PNAS May 28, 2013 vol. 110 no. 22 9136-9141

一次視覚野(V1)の神経活動は、ある刺激と他の刺激の相対的な「価値(その刺激に紐付けられている報酬の量)」にモジュレートされる。そのパターンは「注意」によるモジュレーションと非常によく似ており、実際、価値に強く影響されるニューロンほど注意にも強く影響される。

Stimuli associated with high rewards evoke stronger neuronal activity than stimuli associated with lower rewards in many brain regions. It is not well understood how these reward effects influence activity in sensory cortices that represent low-level stimulus features. Here, we investigated the effects of reward information in the primary visual cortex (area V1) of monkeys. We found that the reward value of a stimulus relative to the value of other stimuli is a good predictor of V1 activity. Relative value biases the competition between stimuli, just as has been shown for selective attention. The neuronal latency of this reward value effect in V1 was similar to the latency of attentional influences. Moreover, V1 neurons with a strong value effect also exhibited a strong attention effect, which implies that relative value and top–down attention engage overlapping, if not identical, neuronal selection mechanisms. Our findings demonstrate that the effects of reward value reach down to the earliest sensory processing levels of the cerebral cortex and imply that theories about the effects of reward coding and top–down attention on visual representations should be unified.

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