Gating of action potential propagation by an axonal A-like potassium conductance in the hippocampus: A new type of non-synaptic plasticity

Synaptic plasticity is usually considered as the main form of activity-dependent functional plasticity in the mammalian brain. Short- and long-term regulation of synaptic transmission have been shown in various types of excitatory synapses including cortical and hippocampal synapses. In this review, we discuss a novel form of non-synaptic plasticity that involves voltage-gated K+ conductances in CA3 pyramidal cell axons. With experimental and theoretical arguments, we show that axons cannot only be considered as a simple structure that transmit reliably the action potential (AP) from the cell body to the nerve terminals. The axon is also able to express conduction failures in specific axonal pathways. We discuss possible physiological conditions in which these axonal plasticity may occur and its incidence on hippocampal network properties. (C) 1999 Editions scientifiques et medicales Elsevier SAS.