Normal Repetitive Firing and Its Pathophysiology

Abstract

A neuron communicates over long distances (more than a few millimeters) by generating a train of impulses which propagates down the axon to release a series of prepackaged quanta of neurotransmitter molecules. The rate, or perhaps the patterning, of the impulse train carries the information. One of the hallmarks of an interictal epileptogenic focus is that many of its neurons are observed to cluster their impulses into bursts, with the intervals between impulses being unusually short (several milliseconds). Is the bursting neuron some sort of pacemaker, driving other normal neurons into synchronous activity and thus spreading the trouble? Or is the bursting one observes just one of those recruited neurons, having nothing more wrong with it than an oversized synaptic input? Or perhaps there are no pacemaker neurons; the trouble could be subtly distributed over many neurons, changing the balance of excitation and inhibition so that the whole circuit tends to go into a bursting-type oscillation.