Interactions among diameter, myelination, and the Na/K pump affect axonal resilience to high-frequency spiking
Yunliang Zang, Eve Marder
Abstract
Significance The reliability of spike propagation in axons is determined by complex interactions among ionic currents, ion pumps, and morphological properties. We use compartment-based modeling to reveal that interactions of diameter, myelination, and the Na/K pump determine the reliability of high-frequency spike propagation. By acting as a “reservoir” of nodal Na + influx, myelinated compartments efficiently increase propagation reliability. Although spike broadening was thought to oppose fast spiking, its effect on spike propagation is complicated, depending on the balance of Na + channel inactivation gate recovery, Na + influx, and axial charge. Our findings suggest that slow Na + removal influences axonal resilience to high-frequency spike propagation and that different strategies may be required to overcome this constraint in different neurons.