Differential conduction at axonal bifurcations. II. Theoretical basis.

1. Numerical methods are employed to describe unbranched and branched axons like those employed in the previous paper (13). The model axon consists of a set of conical-section membrane patches having identical Hodgkin-Huxley (6) properties and which are connected by a finite-difference approximation to the cable equation (7). 2. Frequency-dependent differential conduction is shown to occur in both unbranched and branched axons in the model, much as observed experimentally. 3. The effect is shown to occur when one limb is electrically shorter than another and results from differences in the way in which axial current entering such branches is distributed between membrane area near the bifurcation and membrane area far away.