Roesch Matthew R, Taylor Adam R, Schoenbaum Geoffrey
Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, HSF-2 S251, Baltimore, 21201, USA.
Neuron. 2006 Aug 17;51(4):509-20. doi: 10.1016/j.neuron.2006.06.027.
We monitored single-neuron activity in the orbitofrontal cortex of rats performing a time-discounting task in which the spatial location of the reward predicted whether the delay preceding reward delivery would be short or long. We found that rewards delivered after a short delay elicited a stronger neuronal response than those delivered after a long delay in most neurons. Activity in these neurons was not influenced by reward size when delays were held constant. This was also true for a minority of neurons that exhibited sustained increases in firing in anticipation of delayed reward. Thus, encoding of time-discounted rewards in orbitofrontal cortex is independent of the encoding of absolute reward value. These results are contrary to the proposal that orbitofrontal neurons signal the value of delayed rewards in a common currency and instead suggest alternative proposals for the role this region plays in guiding responses for delayed versus immediate rewards.
我们监测了大鼠眶额皮质中的单神经元活动，这些大鼠执行一项时间折扣任务，其中奖励的空间位置预测奖励发放前的延迟是短还是长。我们发现，在大多数神经元中，短延迟后发放的奖励比长延迟后发放的奖励引发更强的神经元反应。当延迟保持恒定时，这些神经元的活动不受奖励大小的影响。对于少数在预期延迟奖励时表现出持续放电增加的神经元也是如此。因此，眶额皮质中时间折扣奖励的编码与绝对奖励价值的编码无关。这些结果与眶额神经元以通用货币信号延迟奖励价值的提议相反，而是为该区域在指导对延迟奖励与即时奖励的反应中所起的作用提出了替代提议。
