蝇蕈醇小脑齿状-中位核微注射对豚鼠经典眨眼条件反射建立的影响

Microinjection of Muscimol into cerebellular dentate-interpositus nuclei affects acquisition of classical eyeblink conditioning in guinea pigs

目的观察小脑齿状-中位核在豚鼠经典眨眼条件反射建立过程中的作用。方法采用500ms正弦波纯音和100ms束状氧气流的配对刺激，训练豚鼠建立经典眨眼条件反射。在条件反射训练的第4～6天，向豚鼠双侧小脑齿状-中位核微注射蝇蕈醇。整个实验过程中，使用高分辨率的张力换能器检测豚鼠的眨眼反应。结果①蝇蕈醇注射组豚鼠训练第4～6天的条件反应率均显著低于第3训练日水平（P1=0．005，P2=0．004，P，=0．010）；②蝇蕈醇注射组豚鼠训练第7、8天条件反应率仅分别相当于对照组豚鼠第4、5训练日水平（P1=0．061，P2=0．669）；③在此过程中，蝇蕈醇注射组豚鼠非条件眨眼反应的幅度和峰潜伏期均无显著变化（P1=0．926，P2=0．939）。结论小脑齿状．中位核是运动性学习神经回路的重要组成部分，控制着眨眼条件反应的获得和表达。

Objective To investigate the role of cerebellar dentate-interpositus （D-I） nuclei during acquisition of classical eyeblink conditioning in guinea pigs. Methods A 500 ms tone conditioned stimulus （CS） was paired with a 100 ms corneal oxygen-puff unconditioned stimulus （US） in a delay paradigm. Guinea pigs were trained daily to acquire the classically conditioned eyeblink responses. Micorinjections of Muscimol into bilateral cerebellar D-I nuclei were performed during the 4 -6 day of training session. A high-resolution potentiometer was used to detect the eyeblink responses. Results The conditioned response （CR） rates of Muscimolinjected group on session 4 - 6 were significantly lower than their rates on session 3 （ P1 = 0.005, P2 = 0.004, P3 =0. 010） ; Their rates on session 7 and 8 were as the same level as those without microinjection on session 4 and 5 （P1 =0. 061 ,P2 =0.669）. However, there was no significant difference on their amplitude and peak latency of unconditioned responses （URs） during the entire course of training （ P1 = 0. 926, P2 = 0. 939 ）. Conclusion The cerebellar D-I nucleus is actively involved in the neural circuitry of motor learning, which is essential for both acquisition and performance of the classically conditioned eyeblink responses.