STOCHASTIC-MODEL NEURON WITHOUT RESETTING OF DENDRITIC POTENTIAL - APPLICATION TO THE OLFACTORY SYSTEM

A two-dimensional neuronal model, in which the membrane potential of t he dendrite evolves independently from that at the trigger zone of the axon, is proposed and studied. In classical one-dimensional neuronal models the dendritic and axonal potentials cannot be distinguished, an d thus they are reset to resting level after firing of an action poten tial, whereas in the present model the dendritic potential is not rese t. The trigger zone is modelled by a simplified leaky integrator (RC c ircuit) and the dendritic compartment can be described by any of the c lassical one-dimensional neuronal models. The new model simulates obse rved features of the firing dynamics which are not displayed by classi cal models, namely positive correlation between interspike intervals a nd endogenous bursting. It gives a more natural account of features al ready accounted for in previous models, such as the absence of an uppe r limit for the coefficient of variation of intervals (i.e. irregular firing). It allows the first- and second-order neurons of the olfactor y system to be described with the same basic assumptions, which was no t the case in one-point models. Nevertheless it keeps the main qualita tive properties found previously, such as the existence of three regim ens of firing with increasing stimulus concentration and the sigmoid s hape of the firing frequency of first-order neurons as a function of t he logarithm of stimulus concentration.