Individual Fitting of Spatial and Temporal Electrically Evoked Auditory Responses with a Phenomenological Nerve Fiber Model for CI Users
* Presenting author
Individually fitted models of the electrically stimulated auditory nerve might play an important role in improving cochlear implants (CI) speech perception. A fitted model must be able to represent the response of the neural population based on individual patients' electrophysiological data. Most CIs can be used for measuring the nerve's compound activity in the vicinity of every channel-related neural cluster, resulting in a recorded response known as electrically evoked compound action potential (ECAP). In the present work, the auditory nerve was modelled as a population of nerve fibers positioned along the cochlear length. The electrically evoked neural activity of each fiber was modelled using a novel phenomenological model for pulse train stimulation, taking into account the effects of refractoriness and facilitation. All parameters were fitted based on individual ECAP measurements of spatial (spread of excitation) and temporal (refractory recovery) responses. The ECAP amplitude was assumed to be proportional to the total number of spikes obtained with the modelled response. This study shows the feasibility of the novel phenomenological nerve fiber model for an individual fitting procedure. In future work, extending the fitting to psychophysical behavior will enable the evaluation of individual stimulation parameters with the aim to improve CI strategies.