Department of Physiology and Neuroscience, New York University, School of Medicine, 550 First Avenue, New York, NY 10016, USA.
Cerebellum. 2011 Dec;10(4):694-701. doi: 10.1007/s12311-011-0261-6.
The question of what modulates the firing of the cerebellar nuclei (CN) is one to which we presently have a surprisingly incomplete answer. Because most synaptic input to the CN originates from Purkinje cells (PCs), and simple spikes (SSs) are far more numerous than complex spikes (CSs), SSs are generally thought to be the dominant influence on the CN. However, evidence, reviewed here, suggests that this appears not to be the case in some physiologically important situations. As an alternative, we propose that CS activity may have at least as significant an effect on CN firing as do SSs. In particular, we suggest that CS activity has a role in controlling the bursts CN neurons show during various movements, during sleep states, and under ketamine-xylazine anesthesia. The ability to perform this role rests on the fact that CSs can be highly synchronized among PCs that project to the same CN neuron. Specifically, we suggest that synchronized CSs help determine the temporal course of the CN bursts, most often their offset, and that SSs and activity from cerebellar afferents may modulate the specific firing pattern within each burst. This joint control of CN activity may help explain anomalies present in the standard model for synaptic control of CN activity in which determination of CN firing patterns is attributed primarily to SSs.
小脑核（CN）的放电模式由什么来调节是一个我们目前还没有完全答案的问题。由于 CN 的大多数突触输入都来自浦肯野细胞（PCs），而简单 spikes（SSs）的数量远远超过复杂 spikes（CSs），因此通常认为 SSs 对 CN 有主导影响。然而，这里回顾的证据表明，在某些生理上重要的情况下，情况并非如此。作为替代方案，我们提出 CS 活动对 CN 放电的影响至少与 SSs 一样重要。特别是，我们提出 CS 活动在控制 CN 神经元在各种运动、睡眠状态和氯胺酮-甲苯噻嗪麻醉下显示的爆发中发挥作用。能够执行此角色取决于这样一个事实，即投射到同一 CN 神经元的 PC 之间的 CS 可以高度同步。具体来说，我们建议同步 CS 有助于确定 CN 爆发的时间过程，通常是它们的结束，而 SSs 和来自小脑传入的活动可能调节每个爆发中的特定发射模式。对 CN 活动的这种联合控制可能有助于解释在 CN 活动的突触控制的标准模型中存在的异常，其中 CN 放电模式的确定主要归因于 SSs。
