Modelling the cerebellar Purkinje cell: experiments in computo.

Detailed compartmental models of neurons are useful tools for investigating neuronal properties and mechanisms that are not accessible to experimental procedures. If a rigorous approach is used in building the model, simulation studies can be as valuable as laboratory experimentation. As such, modelling becomes an additional method for exploring the function of neurons and nervous systems. As an example, a complex compartmental model with active dendritic membrane of a Purkinje cell is described. The response properties of the model to parallel fiber inputs were investigated. The model fired simple spikes in patterns comparable with those recorded from Purkinje cells in vivo. Synchronous activation of only 20 granule cell inputs was sufficient to generate a measurable response in simulated peri-stimulus histograms. This sensitivity to small excitatory inputs was caused by P-type Ca2+ channels in the dendritic membrane. Such P channels may also be present in the spine heads. Simulations suggest, however, that Ca2+ channels in spine heads cannot be activated by single parallel fiber inputs.