Climbing fibers from the inferior olive make strong excitatory synapses onto cerebellar Purkinje cell (PC) dendrites and trigger distinctive responses known as complex spikes. We found that, in awake mice, a complex spike in one PC suppressed conventional simple spikes in neighboring PCs for several milliseconds. This involved a new ephaptic coupling, in which an excitatory synapse generated large negative extracellular signals that nonsynaptically inhibited neighboring PCs. The distance dependence of complex spike–simple spike ephaptic signaling, combined with the known CF divergence, allowed a single inferior olive neuron to influence the output of the cerebellum by synchronously suppressing the firing of potentially over 100 PCs. Optogenetic studies in vivo and dynamic clamp studies in slice indicated that such brief PC suppression, as a result of either ephaptic signaling or other mechanisms, could effectively promote firing in neurons in the deep cerebellar nuclei with remarkable speed and precision.

来自下橄榄的攀缘纤维在小脑浦肯野细胞 (PC) 树突上形成强烈的兴奋性突触，并触发称为复杂尖峰的独特反应。我们发现，在清醒的小鼠中，一台 PC 中的复杂尖峰抑制了相邻 PC 中传统的简单尖峰数毫秒。这涉及一种新的突触耦合，其中兴奋性突触产生大量的负细胞外信号，非突触地抑制邻近的 PC。复杂尖峰-简单尖峰触觉信号的距离依赖性，结合已知的 CF 发散，允许单个下橄榄神经元通过同步抑制可能超过 100 个 PC 的放电来影响小脑的输出。体内光遗传学研究和切片动态钳研究表明，这种短暂的 PC 抑制，