Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
Neural Netw. 2013 Nov;47:18-31. doi: 10.1016/j.neunet.2012.09.006. Epub 2012 Sep 19.
The output of cerebellar Purkinje cells has been characterized extensively and theories regarding the role of simple spike (SS) and complex spike (CS) patterns have evolved through many different studies. A bistable pattern of SS output can be observed in vitro; however, differing views exist regarding the occurrence of bistable SS output in vivo. Bistability in Purkinje cell output is characterized by abrupt transitions between tonic firing and quiescence, usually evoked by synaptic inputs to the neuron. This is in contrast to the trimodal pattern of activity which has been found in vitro and in vivo when climbing fiber input to Purkinje cells is removed. The mechanisms underlying bistable membrane properties in Purkinje cells have been determined through in vitro studies and computational analysis. In vitro studies have further established that Purkinje cells possess the ability to toggle between firing states, but in vivo studies in both awake and anesthetized animals have found conflicting results as to the presence of toggling in the intact circuit. Here, we provide an overview of the current state of research on bistability, examining the mechanisms underlying bistability and current findings from in vivo studies. We also suggest possible reasons for discrepancies between in vivo studies and propose future studies which would aid in clarifying the role of bistability in the cerebellar circuit.
小脑浦肯野细胞的输出已经得到了广泛的研究，关于简单 spikes (SS) 和复杂 spikes (CS) 模式的作用的理论已经通过许多不同的研究得到了发展。在体外可以观察到 SS 输出的双稳态模式；然而，对于体内 SS 输出的双稳态发生存在不同的观点。浦肯野细胞输出的双稳定性特征是由紧张性放电和静止之间的突然转变，通常由神经元的突触输入引起。这与在体外和体内发现的三模态活动模式形成对比，当去除浦肯野细胞的 climbing 纤维输入时，就会出现这种模式。通过体外研究和计算分析已经确定了浦肯野细胞双稳态膜特性的机制。体外研究进一步证实，浦肯野细胞具有在放电状态之间切换的能力，但在清醒和麻醉动物的体内研究中，对于完整电路中是否存在切换存在相互矛盾的结果。在这里，我们提供了关于双稳定性研究现状的概述，研究了双稳定性的机制以及来自体内研究的当前发现。我们还提出了体内研究之间差异的可能原因，并提出了未来的研究，这将有助于阐明双稳定性在小脑回路中的作用。
