Department of Psychology, Rutgers University, Newark, NJ 07102, United States.
Dev Cogn Neurosci. 2011 Oct;1(4):494-505. doi: 10.1016/j.dcn.2011.07.006.
The human striatum has been previously implicated in the processing of positive reinforcement, but less is known about its role in processing negative reinforcement. In this experiment, participants learn specific approach or avoidance responses, mediated by positive and negative reinforcers respectively to investigate how affective learning and associated neural activity are influenced by the motivational context in which learning occurs. The paradigm was divided into two discrete sessions, where participants could either earn monetary rewards (approach sessions) or avoid monetary losses (avoid sessions) based on successful learning. Specifically, a conditioned cue predicted the chance to win or avoid losing money contingent on a correct button press (pre-learning trials), which upon learning led to the delivery of rewards or termination of losses (post-learning trials). Skin conductance responses (SCRs) and subjective ratings confirmed a learning effect (greater SCRs pre vs. post-learning) irrespective of reinforcer valence. Concurrently, activity in the ventral striatum was characterized by a similar learning effect, with greater responses during pre-learning. Interestingly, such learning effect was enhanced in the presence of a negative reinforcer, as suggested by an interaction between learning phase and session, highlighting the influence negative reinforcers can have on striatal circuits involved in learning and motivated behavior.
人类纹状体先前被认为参与正强化的处理，但对其在负强化处理中的作用知之甚少。在这个实验中，参与者学习特定的趋近或回避反应，分别由正强化和负强化来介导，以研究情感学习和相关的神经活动是如何受到学习发生的动机背景的影响。该范式分为两个不同的阶段，参与者可以根据成功学习来获得金钱奖励（趋近阶段）或避免金钱损失（回避阶段）。具体来说，条件线索预测了在正确按下按钮的情况下获得或避免损失金钱的机会（预学习试验），而学习后则会给予奖励或结束损失（后学习试验）。皮肤电导反应（SCR）和主观评分证实了学习效应（预学习与后学习相比，SCR 更大），而与强化物的效价无关。同时，腹侧纹状体的活动表现出类似的学习效应，在预学习期间反应更大。有趣的是，这种学习效应在存在负强化物的情况下增强，这表明学习阶段和阶段之间的相互作用突显了负强化物对参与学习和动机行为的纹状体回路的影响。
