Belova Marina A, Paton Joseph J, Morrison Sara E, Salzman C Daniel
Department of Neuroscience, Columbia University, New York, NY 10027, USA.
Neuron. 2007 Sep 20;55(6):970-84. doi: 10.1016/j.neuron.2007.08.004.
Animals and humans learn to approach and acquire pleasant stimuli and to avoid or defend against aversive ones. However, both pleasant and aversive stimuli can elicit arousal and attention, and their salience or intensity increases when they occur by surprise. Thus, adaptive behavior may require that neural circuits compute both stimulus valence--or value--and intensity. To explore how these computations may be implemented, we examined neural responses in the primate amygdala to unexpected reinforcement during learning. Many amygdala neurons responded differently to reinforcement depending upon whether or not it was expected. In some neurons, this modulation occurred only for rewards or aversive stimuli, but not both. In other neurons, expectation similarly modulated responses to both rewards and punishments. These different neuronal populations may subserve two sorts of processes mediated by the amygdala: those activated by surprising reinforcements of both valences-such as enhanced arousal and attention-and those that are valence-specific, such as fear or reward-seeking behavior.
动物和人类学会接近并获取愉悦刺激，同时避免或抵御厌恶刺激。然而，愉悦和厌恶刺激都能引发觉醒和注意力，且当它们意外出现时，其显著性或强度会增加。因此，适应性行为可能要求神经回路同时计算刺激效价（或价值）和强度。为探究这些计算是如何实现的，我们研究了灵长类动物杏仁核在学习过程中对意外强化的神经反应。许多杏仁核神经元对强化的反应因强化是否预期而有所不同。在一些神经元中，这种调节仅发生在奖励或厌恶刺激上，而非两者都有。在其他神经元中，预期同样调节对奖励和惩罚的反应。这些不同的神经元群体可能服务于由杏仁核介导的两种过程：那些由两种效价的意外强化激活的过程，如增强的觉醒和注意力；以及那些效价特异性的过程，如恐惧或寻求奖励行为。
