Role of striatal GABAergic neuron system in learning behavior

纹状体不仅参与感觉或运动控制，还参与记忆和学习等认知功能。我们研究了纹状体kainic酸损伤对各种学习行为的影响，它诱导纹状体中的选择性神经元细胞死亡。纹状体损伤的大鼠在空间学习任务中表现出严重的缺陷，但在辨别学习和经典条件反射方面没有任何缺陷。本研究探讨了纹状体神经元，特别是gaba能神经元在学习记忆中的作用。在每次试验前系统给予GABA_A激动剂可显著改善纹状体kainic酸损伤大鼠Morris水迷宫和径向迷宫任务的表现，而GABA_B激动剂则无明显改善作用。这表明，大脑中的GABA_A受体与纹状体损伤动物的学习缺陷有关。由于纹状体GABA神经元投射到三个区域，我们随后测试了微量注射GABA_A拮抗剂对正常大鼠径向迷宫行为的影响。结果表明，黑质网状部注射对错误次数的增加最为明显，纹状体注射对错误次数也有显著影响。综上所述，包含纹状体的神经回路，特别是纹状体gaba能神经元系统，在空间记忆任务的表现中起着重要作用。

The striatum has been suggested to be involved not only in the sensory or motor control but also in cognitive function such as memory and learning. We have investigated the effects of striatal kainic acid lesions, which induce selective neuronal cell death in the striatum, on various kinds of learning behavior. Rats with striatal lesions showed severe deficits in spatial learning tasks though they did not show any deficits in discrimination learning and classical conditioning. The present study investigated the mechanism of learning deficits in these animals and the role of striatal neurons, especially striatal GABAergic neurons, in learning and memory.GABA_A agonist systemically administered before each trial significantly improved the performance of Morris water maze and radial maze tasks in rats with striatal kainic acid lesions, while GABA_B agonist did not. This suggests that GABA_A receptors in the brain are involved in the learning deficits of striatal lesioned animals. Since there are three areas to which striatal GABA neurons project, we then tested the effects of microinjection of GABA_A antagonist on radial maze behavior using normal rats previously trained in this task. As a result, injection into the substantia nigra pars reticulata most distinctly increased the number of errors, and injection into the striatum also had significant effects. Taken together it was suggested that a neural circuit containing the striatum, especially the strionigral GABAergic neuron system, plays an important role in performance of spatial memory tasks.