The composite neuron: A realistic one-compartment purkinje cell model suitable for large-scale neuronal network simulations

We present a simple method for the realistic description of neurons that is well suited to the development of large-scale neuronal network models wher e the interactions within and between neural circuits are the object of stu dy rather than the details of dendritic signal propagation in individual ce lls. Referred to as the composite approach, it combines in a one-compartmen t model elements of both the leaky integrator cell and the conductance-base d formalism of Hodgkin and Huxley (1952). Composite models treat the cell m embrane as an equivalent circuit that contains ligand-gated synaptic, volta ge-gated, and voltage- and concentration-dependent conductances. The time d ependences of these various conductances are assumed to correlate with thei r spatial locations in the real cell. Thus, when viewed from the soma, liga nd-gated synaptic and other dendritically located conductances can be model ed as either single alpha or double exponential functions of time, whereas, with the exception of discharge-related conductances, somatic and proximal dendritic conductances can be well approximated by simple current-voltage relationships. As an example of the composite approach to neuronal modeling we describe a composite model of a cerebellar Purkinje neuron.