Rokni Dan, Tal Zohar, Byk Hananel, Yarom Yosef
Department of Neurobiology, Institute of Life Sciences, and Interdisciplinary Center for Neural Computation, Hebrew University Jerusalem, Israel.
Front Cell Neurosci. 2009 Nov 9;3:12. doi: 10.3389/neuro.03.012.2009. eCollection 2009.
Recent studies have demonstrated that the membrane potential of Purkinje cells is bi-stable and that this phenomenon underlies bi-modal simple spike firing. Membrane potential alternates between a depolarized state, that is associated with spontaneous simple spike firing (up state), and a quiescent hyperpolarized state (down state). A controversy has emerged regarding the relevance of bi-stability to the awake animal, yet recordings made from behaving cat Purkinje cells have demonstrated that at least 50% of the cells exhibit bi-modal firing. The robustness of the phenomenon in vitro or in anaesthetized systems on the one hand, and the controversy regarding its expression in behaving animals on the other hand suggest that state transitions are under neuronal control. Indeed, we have recently demonstrated that synaptic inputs can induce transitions between the states and suggested that the role of granule cell input is to control the states of Purkinje cells rather than increase or decrease firing rate gradually. We have also shown that the state of a Purkinje cell does not only affect its firing but also the waveform of climbing fiber-driven complex spikes and the associated calcium influx. These findings call for a reconsideration of the role of Purkinje cells in cerebellar function. In this manuscript we review the recent findings on Purkinje cell bi-stability and add some analyses of its effect on the regularity and variability of Purkinje cell activity.
最近的研究表明，浦肯野细胞的膜电位是双稳态的，并且这种现象是双峰简单锋电位发放的基础。膜电位在与自发简单锋电位发放相关的去极化状态（上状态）和静止的超极化状态（下状态）之间交替。关于双稳态与清醒动物的相关性已经出现了争议，然而，对行为猫浦肯野细胞的记录表明，至少50%的细胞表现出双峰发放。一方面，该现象在体外或麻醉系统中很稳健，另一方面，关于其在行为动物中的表达存在争议，这表明状态转换受神经元控制。事实上，我们最近证明突触输入可以诱导状态之间的转换，并表明颗粒细胞输入的作用是控制浦肯野细胞的状态，而不是逐渐增加或降低发放率。我们还表明，浦肯野细胞的状态不仅影响其发放，还影响攀缘纤维驱动的复合锋电位的波形以及相关的钙内流。这些发现需要重新考虑浦肯野细胞在小脑功能中的作用。在本手稿中，我们回顾了关于浦肯野细胞双稳态的最新发现，并对其对浦肯野细胞活动的规律性和变异性的影响进行了一些分析。
