Evaluation of a model of the cochlear neural membrane. I. Physiological measurement of membrane characteristics in response to intrameatal electricalstimulation

To understand the auditory neural response to electrical stimuli similar to those used in a cochlear implant, it will be necessary to understand the n eural refraction and summation response kinetics. Evidence exists indicatin g that the cell soma may alter the auditory neural response kinetics and co uld be the site of conduction failure for excitation initiated on the perip heral process. There is, however, reason to believe that the excitation sit e in some healthy, type I neurons and in pathological, type III neurons is the central process of the cell. To characterize the neural response to act ivation at a controlled central process site, cat auditory neurons were sti mulated with an intrameatal electrode, and the summation and refraction res ponse kinetics were measured. This approach was used to: (1) characterize t he behavior of the neural response to central process excitation; (2) make comparisons between intrameatal excitation at a known central site and scal a tympani excitation at an unknown site; and (3) provide membrane character ization free from the possible alteration of membrane kinetics produced by the cell soma. The membrane kinetics measured using intrameatal stimulation differ from those recorded with scala tympani stimulation indicating that the mechanisms for scala tympani and intrameatal stimulation differ. (C) 20 00 Elsevier Science B.V. All rights reserved.