Mechanisms Supporting Transfer of Inhibitory Signals into the Spike Output of Spontaneously Firing Cerebellar Nuclear Neurons In Vitro

• DOI: 10.1007/s12311-009-0153-1
• Publication Date: 2010-02-10T19:16:27Z
• Authors: Christine M. Pedr...
• Keywords: Neurons; 0301 basic medicine; Patch-Clamp Techniques; Action Potentials; Neural Inhibition; Signal Processing, Computer-Assisted; Synaptic Transmission; Mice, Inbred C57BL; Mice; Purkinje Cells; 03 medical and health sciences; Organ Culture Techniques; Cerebellar Nuclei; Inhibitory Postsynaptic Potentials; Animals

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.