What happens to conduction when an axon loses its myelin? · Grey Matter

Without the insulation, current from each node leaks out along the bare stretch before it reaches the next node, and the sodium channels it needs are concentrated at the nodes, with few under the old sheath.

What happens to conduction when an axon loses its myelin?

Without the insulation, current from each node leaks out along the bare stretch before it reaches the next node, and the sodium channels it needs are concentrated at the nodes, with few under the old sheath. The spike may slow, fail to cross the gap, or get through only at low firing rates, and signals that should arrive together lose their timing. In multiple sclerosis the immune system damages myelin in the brain and spinal cord, and the symptoms (blurred vision, weakness, numbness) depend on which tracts are hit. Partial recovery comes from redistributing sodium channels along the bare axon and from new myelin made by precursor cells, which is often thinner than the original.