Laboratory of Psychobiology, Campus Santiago Ramón y Cajal, University of Sevilla, Camilo Jose Cela s/n, Seville 41018, Spain.
Neuroscience. 2010 Mar 10;166(1):49-60. doi: 10.1016/j.neuroscience.2009.12.018. Epub 2009 Dec 16.
The cerebellum of mammals is an essential component of the neural circuitry underlying classical conditioning of eyeblink and other discrete responses. Although the neuroanatomical organization of the cerebellum is notably well conserved in vertebrates, little is actually known about the cerebellar learning functions in nonmammal vertebrate groups. In this work we studied whether the cerebellum of teleost fish plays a critical role in the classical conditioning of a motor response. In Experiment 1, we classically conditioned goldfish in a procedure analogous to the eyeblink conditioning paradigm commonly used in mammals. Goldfish were able to learn to express an eyeblink-like conditioned response to a predictive light (conditioned stimulus) that was paired with a mild electric shock (unconditioned stimulus). The application of unpaired and extinction control procedures demonstrated that also in teleosts the learning of this motor response depends on associative rules. In Experiment 2 we studied whether classical conditioning of this response is critically dependent on the cerebellum and independent of telencephalic structures as occurs in mammals. Cerebellum lesion prevented the acquisition of the eyeblink-like conditioned response whereas telencephalon ablation did not impair the learning of this response. No deficit was observed following lesions in the performance of the unconditioned response or in the percentage of spontaneous responses. These results suggest that cerebellum ablation in goldfish affects a critical component of the circuitry necessary for the acquisition of the conditioned response but does not interfere with the ability of the animal to perform the response itself. The striking similarity in the role of cerebellum in classical conditioning of a motor response between teleost fish and mammals suggests that this learning function of the cerebellum could be a primitive feature of the vertebrate brain that has been conserved through evolution.
哺乳动物的小脑是经典眨眼和其他离散反应条件反射神经回路的重要组成部分。尽管小脑的神经解剖结构在脊椎动物中显著保守，但实际上对于非哺乳动物脊椎动物群体的小脑学习功能知之甚少。在这项工作中，我们研究了硬骨鱼的小脑是否在运动反应的经典条件反射中起关键作用。在实验 1 中，我们以类似于哺乳动物常用的眨眼条件反射范式的程序对金鱼进行经典条件反射。金鱼能够学习对预测光（条件刺激）表达眨眼样条件反应，该光与轻度电击（非条件刺激）配对。未配对和消光控制程序的应用表明，在硬骨鱼中，这种运动反应的学习也依赖于联想规则。在实验 2 中，我们研究了这种反应的经典条件反射是否严重依赖于小脑，并且不依赖于哺乳动物中出现的端脑结构。小脑损伤阻止了眨眼样条件反应的获得，而端脑切除不会损害这种反应的学习。未观察到未配对反应或自发反应百分比的表现缺陷。这些结果表明，在金鱼中，小脑损伤会影响获得条件反应所需的电路的关键组成部分，但不会干扰动物执行反应本身的能力。小脑在硬骨鱼和哺乳动物经典运动反应条件反射中的作用惊人相似，这表明小脑的这种学习功能可能是脊椎动物大脑的原始特征，已通过进化得以保守。
