Tye Kay M, Janak Patricia H
Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, USA.
J Neurosci. 2007 Apr 11;27(15):3937-45. doi: 10.1523/JNEUROSCI.5281-06.2007.
Lesion studies demonstrate that the basolateral amygdala complex (BLA) is important for assigning motivational significance to sensory stimuli, but little is known about how this information is encoded. We used in vivo electrophysiology procedures to investigate how the amygdala encodes motivating and reinforcing properties of cues that induce reinstatement of reward-seeking behavior. Two groups of rats were trained to respond to a sucrose reward. The "paired" group was trained with a reward-predictive cue, whereas the "unpaired" group was trained with a randomly presented cue. Both groups underwent identical extinction and reinstatement procedures during which the reward was withheld. The proportion of neurons that were phasically cue responsive during reinstatement was significantly higher in the paired group (46 of 100) than in the unpaired group (8 of 112). Cues that induce reward-seeking behavior can do so by acting as incentives or reinforcers. Distinct populations of neurons responded to the cue in trials in which the cue acted as an incentive, triggering a motivated reward-seeking state, or as a reinforcer, supporting continued instrumental responding. The incentive motivation-encoding population of neurons (34 of 46 cue-responsive neurons; 74%) extinguished in temporal agreement with a decrease in the rate of instrumental responding. The conditioned reinforcement-encoding population of neurons (12 of 46 cue-responsive neurons; 26%) maintained their response for the duration of cue-reinforced instrumental responding. These data demonstrate that separate populations of cue-responsive neurons in the BLA encode the motivating or reinforcing properties of a cue previously associated with a reward.
损伤研究表明，基底外侧杏仁核复合体（BLA）对于赋予感觉刺激动机意义很重要，但对于该信息如何编码却知之甚少。我们使用体内电生理学方法来研究杏仁核如何编码诱导寻求奖励行为恢复的线索的动机和强化特性。两组大鼠被训练对蔗糖奖励做出反应。“配对”组用奖励预测线索进行训练，而“非配对”组用随机呈现的线索进行训练。两组都经历了相同的消退和恢复程序，在此期间奖励被 withheld。在恢复过程中对线索有相位反应的神经元比例，配对组（100个中有46个）显著高于非配对组（112个中有8个）。诱导寻求奖励行为的线索可以通过充当激励物或强化物来做到这一点。在不同的试验中，不同的神经元群体对线索做出反应，在这些试验中，线索充当激励物，引发有动机的寻求奖励状态，或充当强化物，支持持续的工具性反应。编码激励动机的神经元群体（46个线索反应神经元中的34个；74%）与工具性反应速率下降同步在时间上消退。编码条件性强化的神经元群体（46个线索反应神经元中的12个；26%）在线索强化的工具性反应持续期间保持其反应。这些数据表明，BLA中不同的线索反应神经元群体编码了先前与奖励相关的线索的激励或强化特性。
