<P> Saltatory conduction in myelinated axons requires organization of the nodes of Ranvier, whereas voltage - gated sodium channels are highly populated . Studies show that αII - Spectrin, a component of the cytoskeleton is enriched at the nodes and paranodes at early stages and as the nodes mature, the expression of this molecule disappears . It is also proven that αII - Spectrin in the axonal cytoskeleton is absolutely vital for stabilizing sodium channel clusters and organizing the mature node of Ranvier . </P> <P> It has been shown previously that OMgp (oligodendrocyte myelin glycoprotein) clusters at nodes of Ranvier and may regulate paranodal architecture, node length and axonal sprounting at nodes . However, a follow - up study showed that the antibody used previously to identify OMgp at nodes crossreacts with another node - enriched component versican V2 and that OMgp is not required for the integrity of nodes and paranodes, arguing against the previously reported localization and proposed functions of OMgp at nodes . </P> <P> An action potential is a spike of both positive and negative ionic discharge that travels along the membrane of a cell . The creation and conduction of action potentials represents a fundamental means of communication in the nervous system . Action potentials represent rapid reversals in voltage across the plasma membrane of axons . These rapid reversals are mediated by voltage - gated ion channels found in the plasma membrane . The action potential travels from one location in the cell to another, but ion flow across the membrane occurs only at the nodes of Ranvier . As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath . The clustering of voltage - gated sodium and potassium ion channels at the nodes permits this behavior . </P> <P> Since an axon can be unmyelinated or myelinated, the action potential has two methods to travel down the axon . These methods are referred to as continuous conduction for unmyelinated axons, and saltatory conduction for myelinated axons . Saltatory conduction is defined as an action potential moving in discrete jumps down a myelinated axon . </P>

Where are voltage gated sodium channels concentrated in myelinated axons