Evaluation of a model of the cochlear neural membrane. II: comparison of model and physiological measures of membrane properties measured in response to intrameatal electrical stimulation.

This study examines existing equation sets describing neural membrane ionic currents, such as the Hodgkin-Huxley (1952) equations, used to define the membrane currents in a numerical model of the auditory neuron and determines their adequacy for modeling the summation and refraction properties of auditory neurons in response to electrical stimulation. Specifically, the summation and refraction time constants of each equation set are compared to physiological measures of these time constants. Since previous studies have shown the cell body and peripheral process of the auditory neuron may influence the measurement of neural time constants, the physiological time constants used for comparison are those which were recorded using intrameatal electrical stimulation. The intrameatal electrode should stimulate the neuron in an area where the axon has a uniform geometry. Accordingly, the neural model used to duplicate this experiment was also of uniform geometry. Of the membrane equation sets evaluated, none was clearly superior for modeling both the refraction and summation properties of the auditory neuron, though some equation sets were capable of accurately modeling either the refraction or the summation properties, provided operating temperatures were adjusted to provide appropriate kinetics.