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Title: Pulsatile electrical stimulation of auditory nerve fibres : a modelling approach
Author: Chen, Xisha
ISNI:       0000 0004 2748 5618
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2012
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A stochastic leaky integrate-and-fire nerve model with a dynamical threshold (LIFDT) has been derived for the neural response to sinusoidal electrical stimulation. The LIFDT model incorporates both the refractory effects and the accommodation effects in the interpulse interactions. In this thesis, this phenomenological nerve model is extended for the neural response to pulsatile electrical stimulation, which is widely used in cochlear implants as it reduces inter channel interference. Neurophysiological data from adult guinea pigs were fitted to the LIFDT model. First, the parameters were constrained by the Input/output (I/O) curve analysis. Analysis of the data showed strong accommodation effects. The figures of I/O function for each pulse were plotted according to the physiological data. Fitting the I/O function of the data constrained the value of four variables of LIFDT model. The other five parameters were “optimised by eye”. Although the LIFDT is built with stimulus-dependent threshold, the response of short duration biphasic pulsatile stimuli exhibits weak accommodation effects. Then, in order to avoid the complication of full optimization, analytical approximation of the LIFDT model was derived for pulsatile electrical stimulation. It improves computational efficiency and provides information on how the parameters of the LIFDT model affect the accommodation effects. Theoretical predictions indicate that the LIFDT model could not capture the strong accommodation effects in the neurophysiological data due to structural problems. Alternatively, a Markov renewal process model was utilized to track the pulsetrain response. The stationary and non-stationary Markov renewal process models were fitted to the neurophysiological data. Both models can interpret the conventional PST histograms into conditional probabilities, which are directly related to the interpulse intervals. The consistent results from those two models provide a qualitative analysis of the accommodation characteristics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QP Physiology ; TK Electrical engineering. Electronics Nuclear engineering