A detailed multicompartmental model was used to study neuronal electroresponsiveness of cerebellar granule cells in rats. Here we show that, in cerebellar granule cells, Na+ channels are enriched in the axon, especially in the hillock, but almost absent from soma and dendrites. Numerical simulations indicated that granule cells have a compact electrotonic structure allowing EPSPs to diffuse with little attenuation from dendrites to axon. The spike arose almost simultaneously along the whole axonal ascending branch and invaded the hillock, whose activation promoted spike back-propagation with marginal delay (<200 micros) and attenuation (<20 mV) into the somato-dendritic compartment. For details check the cited article.
Model Type: Neuron or other electrically excitable cell
Region(s) or Organism(s): Cerebellum
Cell Type(s): Cerebellum interneuron granule GLU cell
Currents: I A; I M; I h; I K,Ca; I Sodium; I Calcium; I Potassium; I A, slow
Model Concept(s): Action Potential Initiation; Active Dendrites; Detailed Neuronal Models; Axonal Action Potentials; Action Potentials; Intrinsic plasticity
Simulation Environment: NEURON
Implementer(s): Diwakar, Shyam [shyam at amrita.edu]
References:
Diwakar S, Magistretti J, Goldfarb M, Naldi G, D'Angelo E. (2009). Axonal Na+ channels ensure fast spike activation and back-propagation in cerebellar granule cells. Journal of neurophysiology. 101 [PubMed]