INFLUENCE OF DENDRITIC STRUCTURE ON FIRING PATTERN IN MODEL NEOCORTICAL NEURONS

NEOCORTICAL neurons display a wide range of dendritic morphologies, ra nging from compact arborizations to highly elaborate branching pattern s(1). In vitro electrical recordings from these neurons have revealed a correspondingly diverse range of intrinsic firing patterns, includin g non-adapting, adapting and bursting types(2,3). This heterogeneity o f electrical responsivity has generally been attributed to variability in the types and densities of ionic channels. We show here, using com partmental models of reconstructed cortical neurons, that an entire sp ectrum of firing patterns can be reproduced in a set of neurons that s hare a common distribution of ion channels and differ only in their de ndritic geometry. The essential behaviour of the model depends on part ial electrical coupling of fast active conductances localized to the s oma and axon and slow active currents located throughout the dendrites , and can be reproduced in a two-compartment model. The results sugges t a causal relationship for the observed correlations between dendriti c structure and firing properties(3-7) and emphasize the importance of active dendritic conductances in neuronal function(8-10).