Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried Müller Str. 27, Tübingen, Germany.
Cerebellum. 2010 Mar;9(1):67-76. doi: 10.1007/s12311-009-0153-1.
Cerebellar cortical signals are carried to their principal target, the deep cerebellar nuclear neurons (DCNs), via the inhibitory pathway formed by Purkinje cell (PC) axons. Two different intrinsic properties of DCNs, rebound excitation and automatic firing, have been proposed to support ensuing mechanisms for information transfer via inhibitory synapses. The efficacy of these mechanisms was investigated using whole-cell recordings of spontaneously firing DCNs in cerebellar slices. Results using current injection revealed that both mechanisms are effective in spontaneously firing DCNs but operate at different ranges of membrane potential. Rebound frequency was well correlated to the duration and amplitude of the preceding hyperpolarization. Activation of PC synapses with trains of stimuli few seconds long elicited rebound firing in all tested neurons, demonstrating that inhibition can elicit rebounds in DCNs held at their spontaneous membrane potential. Rebounds could be also elicited by single stimulus in a subset of neurons. The rebound frequency was significantly correlated to the synaptic stimulus strength, supporting the idea that rebound frequency may encode the amplitude of inhibition and thus serve to transfer inhibitory signals in the cerebellar circuit.
小脑皮层信号通过浦肯野细胞 (PC) 轴突形成的抑制性通路传递到它们的主要靶标——深部小脑核神经元 (DCN)。DCN 具有两种不同的内在特性，即反弹兴奋和自动放电，这两种特性被提议用于支持通过抑制性突触进行信息传递的后续机制。使用小脑切片中自发放电的 DCN 的全细胞膜片钳记录来研究这些机制的效果。电流注入的结果表明，这两种机制在自发放电的 DCN 中都有效，但在不同的膜电位范围内起作用。反弹频率与先前去极化的持续时间和幅度密切相关。用几秒钟长的刺激序列激活 PC 突触可在所有测试的神经元中引发反弹放电，表明抑制作用可在 DCN 的自发膜电位下引发反弹。在一部分神经元中，单个刺激也可以引发反弹。反弹频率与突触刺激强度显著相关，支持反弹频率可能编码抑制幅度的观点，从而用于在小脑回路中传递抑制性信号。
