Han J S, McMahan R W, Holland P, Gallagher M
Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
J Neurosci. 1997 May 15;17(10):3913-9. doi: 10.1523/JNEUROSCI.17-10-03913.1997.
The present study examined the role of an amygdalo-nigrostriatal pathway in associative learning. An asymmetrical lesion model was used to test whether a circuit from the amygdala central nucleus to the dorsolateral striatum, via the substantia nigra, is critical for mediating conditioned orienting responses. Rats with an asymmetrical lesion, consisting of neurotoxic removal of central nucleus neurons in one hemisphere and depletion of the dopamine innervation of the dorsolateral striatum in the contralateral hemisphere, failed to acquire conditioned orienting responses. In contrast, the asymmetrical lesion had no effect on spontaneous orienting or learning another response directed to the source of the food unconditioned stimulus in the same task. A second experiment tested the effect of reversible inactivation of the dorsolateral striatum contralateral to a neurotoxic central nucleus lesion on acquisition of the conditioned orienting response. Although inactivation did not affect spontaneous orienting, rats failed to acquire the conditioned orienting response during sessions in which inactivation occurred. Immediately after the inactivation procedure was terminated, however, a significant increase in orienting to the conditioned stimulus was evident. These data support the interpretation that the dorsolateral striatum provides a route for the expression of the conditioned orienting response but is not essential for acquisition of this learned behavior.
本研究考察了杏仁核 - 黑质 - 纹状体通路在联想学习中的作用。采用不对称损伤模型来测试一条从杏仁核中央核经黑质至背外侧纹状体的神经回路对于介导条件性定向反应是否至关重要。具有不对称损伤的大鼠，即一侧半球的中央核神经元经神经毒性去除，对侧半球背外侧纹状体的多巴胺神经支配耗竭，未能习得条件性定向反应。相比之下，这种不对称损伤对自发定向或在同一任务中学习针对食物非条件刺激源的另一种反应没有影响。第二个实验测试了在神经毒性中央核损伤对侧的背外侧纹状体可逆失活对条件性定向反应习得的影响。虽然失活不影响自发定向，但在失活期间的实验中，大鼠未能习得条件性定向反应。然而，在失活程序终止后，对条件刺激的定向显著增加。这些数据支持这样的解释，即背外侧纹状体为条件性定向反应的表达提供了一条途径，但对于这种习得行为的获得并非必不可少。
