Capacitance and Myelination vs. Conduction Velocity Mengqi Xing, Basheer Subei, Rafael Romero

Membrane Thickness Soliton Model of Action Potentials – Soliton (mechanical wave) propagates along membrane that causes AP – Thermodynamically sound – Δ in membrane thickness = Δ in Capacitance Piezoelectricity

Myelin Distribution Myelin sheaths – Δ membrane thickness Δ membrane capacitance – Speed up AP propagation Distribution of Myelin – Nodes of Ranvier Hodgkin-Huxley Model – Myelination Passive Cable Model

Methods Testing Spatial Distribution of Myelin: – 6 Different Distributions – Control, Full, Short, Long, Mid Gap, Multiple Gap – Scaled up axon dimensions Studying: – Effect of Membrane Thickness/Distribution – Significance of Nodes of Ranvier – Conductance velocity

Different Distributions Control Short Myelin Full Long Myelin Mid GapMultiple Gap

Control

Full Myelin

Short Myelin

Long Myelin

Mid Gap Myelin

Multiple Gap

Average Conduction Velocity ControlMultiple GapMid GapFull Velocity (m/s)

Discussion Main Points: – Myelination Fast conduction BUT AP decays No gates ∴ no current to recharge AP – No myelination Signal Slow Gates throughout axon allow propagation Nodes of Ranvier – Recharge AP & prevent signal decay

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