Figure 9. Mathematical model of the hyperthermia-induced changes in excitability of sensory axons.

The open circles indicate the Bostock model as modified for sensory axons (Howells et al. 2012), and the modelled changes during hyperthermia are shown as closed circles. Hyperthermia was modelled by an increase in temperature of 6°C (with the activation kinetics and maximum conductances increased according to their Q₁₀ values; see Methods section), a hyperpolarization of the half-activation voltage of I_h (7 mV) and a small additional depolarizing current of 30 pA. A, depolarizing threshold electrotonus for +40% and +20% of the control threshold. B, hyperpolarizing threshold electrotonus (−20%, −40%, −70% and −100%). C, current–threshold relationship. D, the recovery of excitability after a supramaximal stimulus.