Corbit Laura H, Janak Patricia H
Ernest Gallo Clinic and Research Center, University of California at San Francisco, Emeryville, California 94608, USA.
J Neurosci. 2007 Dec 19;27(51):13977-81. doi: 10.1523/JNEUROSCI.4097-07.2007.
Conditioned stimuli are important guides for behavioral actions. This experiment determined the role of the dorsal striatum in conditioned-stimulus modulation of instrumental responding using the pavlovian-instrumental transfer (PIT) paradigm. Rats received pavlovian training wherein two different auditory stimuli predicted the delivery of two food rewards. Next, rats were trained to perform two instrumental actions earning the same two rewards. Finally, the impact of pavlovian stimuli on instrumental performance was assessed in extinction: the stimuli were periodically presented while rats were free to perform the lever-press response. Before testing, medial or lateral dorsal striatum was infused with saline or baclofen/muscimol, to temporarily inactivate the region. Under saline, outcome-selective PIT was observed: presentation of a stimulus paired with the same outcome as the instrumental action elevated responding, whereas presentation of a stimulus paired with a different outcome did not. Inactivation of the dorsolateral striatum dramatically reduced this effect. Inactivation of the dorsomedial striatum left intact the ability of reward-related stimuli to invigorate responding; however, the selectivity of the stimulus effect was lost (i.e., both stimuli excited responding). These results indicate that subregions of the dorsal striatum play distinct roles in stimulus modulation of instrumental performance with the lateral region being vital for reward-related stimuli to excite responding and the medial region being involved in the integration of stimulus-reward associations with specific response-outcome associations to produce selective responding. These findings identify new roles for the dorsal striatum in mediating the incentive effects of reward-predictive stimuli on behavioral actions made to obtain reward.
条件刺激是行为动作的重要指导。本实验使用巴甫洛夫式工具性转移（PIT）范式确定了背侧纹状体在工具性反应的条件刺激调节中的作用。大鼠接受巴甫洛夫训练，其中两种不同的听觉刺激预测两种食物奖励的发放。接下来，训练大鼠执行两种工具性动作以获得相同的两种奖励。最后，在消退阶段评估巴甫洛夫刺激对工具性表现的影响：在大鼠自由进行杠杆按压反应时定期呈现刺激。在测试前，向内侧或外侧背侧纹状体注入生理盐水或巴氯芬/蝇蕈醇，以暂时使该区域失活。在注入生理盐水的情况下，观察到结果选择性PIT：呈现与工具性动作相同结果配对的刺激会提高反应，而呈现与不同结果配对的刺激则不会。背外侧纹状体失活显著降低了这种效应。背内侧纹状体失活后，与奖励相关的刺激激发反应的能力保持不变；然而，刺激效应的选择性丧失了（即两种刺激都激发反应）。这些结果表明，背侧纹状体的亚区域在工具性表现的刺激调节中发挥着不同的作用，外侧区域对于与奖励相关的刺激激发反应至关重要，内侧区域参与刺激 - 奖励关联与特定反应 - 结果关联的整合以产生选择性反应。这些发现确定了背侧纹状体在介导奖励预测性刺激对为获得奖励而做出的行为动作的激励作用方面的新作用。
