Simulation of Intrinsic Bursting in CA3 Hippocampal Neurons

Dendritic recordings from hippocampal pyramidal cells suggest that bursts of action potentials--riding on a depolarizing wave and terminating in a slow calcium-mediated spike--can be generated locally in the dendrites, as well as at the soma. These data necessitated revision of our earlier model in which bursts at the soma are generated by interaction of two spatially separated conductance systems--a fast-spike sodium mechanism at the soma and a slow-spike calcium mechanism on the apical dendrite. We have introduced into a model of the CA3 hippocampal neuron two experimentally testable concepts: voltage-dependent inactivation of Ik and partial inactivation of ICa by Ca2+ ion. With these mechanisms, the model accurately reproduces bursts generated in either soma or in the apical dendrites by sets of conductances all located in the same respective membrane region. The model is also capable of bursting repetitively in response to continuous stimulation.