Online Seminar - Signal propagation in myelinated axons: relating structure to function using mathematical modeling and simulations

The profound functional significance of myelin is revealed by the severe neurological deficits that are consequent upon multiple inherited or acquired demyelinating conditions. Recent observations demonstrate that the dimensions of myelin sheaths relative to axon calibers can be modulated in response to adult experience with significant functional consequences. Despite the growing evidence that such plasticity plays a key role in both normal and abnormal nervous system function, the effects of such myelin and axonal organization changes on signal propagation are not clearly understood.

In this talk, I will present new results relating signal transmission in myelinated axons and the fiber geometry. I will consider an electrical model of the myelinated axon based on cable theory and on Hodgkin-Huxley type formalism to represent voltage gated channels at the nodes of Ranvier (NoR). Using mathematical analysis and simulations, I will show that the different frequencies constituting a signal travel at their own speed, that depends on the fiber properties. I will propose an analytical formula for the signal transmission threshold separating a successful transmission from one node to an other, to a failure in transmission. I will then show how we can relate this result to the diversity of myelin thickness and g- ratios observed in data.
 

This seminar will be held online via Zoom. Details in attached poster.