The optokinetic response (OKR), a reflexive eye movement evoked by a motion of the visual field, is known to adapt its strength to cope with an environmental change throughout life, which is a type of cerebellum-dependent learning. Previous studies suggested that OKR learning induces changes in in-vivo spiking activity and synaptic transmission of the cerebellar Purkinje cell (PC). Despite the recent emphasis on the importance of the intrinsic excitability related to learning and memory, the direct correlation between the intrinsic excitability of PCs and OKR learning has not been tested. In the present study, by utilizing the whole-cell patch-clamp recording, we compared the responses of cerebellar PCs to somatic current injection between the control and learned groups. We found that the neurons from the learned group showed a significant reduction in mean firing rate compared with neurons in the control group. In the analysis of single action potential (AP), we revealed that the rheobase current for the generation of single AP was increased by OKR learning, while AP threshold, AP amplitude, and afterhyperpolarization amplitude were not altered. Taken together, our result suggests that the decrease in the intrinsic excitability was induced in the cerebellar PC of learned group by an increase in the current threshold for generating AP.

中文翻译：

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小鼠视动学后小脑浦肯野细胞内在兴奋性降低

视动反应（OKR）是一种由视野运动引起的反射性眼球运动，众所周知，它可以调节其力量来应对一生中环境的变化，这是一种依赖于小脑的学习。先前的研究表明，OKR学习可诱导小脑浦肯野细胞（PC）的体内突增活性和突触传递的变化。尽管最近强调了与学习和记忆有关的内在兴奋性的重要性，但尚未测试PC的内在兴奋性与OKR学习之间的直接相关性。在本研究中，通过利用全细胞膜片钳记录，我们比较了对照组和学习组之间小脑PC对体电流注入的反应。我们发现，与对照组的神经元相比，学习组的神经元平均放电率显着降低。在单动电位（AP）分析中，我们发现通过OKR学习可以增加用于生成单个AP的流变碱电流，而不会改变AP阈值，AP振幅和超极化后振幅。两者合计，我们的结果表明，内在兴奋性的降低是由学习群体小脑PC电流阈值的增加引起的。超极化后的振幅没有改变。两者合计，我们的结果表明，内在兴奋性的降低是由学习群体小脑PC电流阈值的增加引起的。超极化后的振幅没有改变。两者合计，我们的结果表明，内在兴奋性的降低是由学习群体小脑PC电流阈值的增加引起的。