Graeme Clark Collection

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End date: 1999 × Subject: cochlear implant × Subject: electrical stimulation × Author: O'Leary, Stephen × Start date: 1990 ×

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Now showing 1 - 4 of 4
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    Discharge rate-level functions from dorsal cochlear nucleus single units in response to acoustic and electrical stimulation of the auditory nerve
    O'Leary, S. J. ; Clark, Graeme M. ; Tong, Y. C. ( 1995)
    Discharge rate-level (I/O) functions possessed by dorsal cochlear nucleus (DCN) units were examined, in response to bipolar electrical stimulation of the cochlea of the barbiturate-anesthetized cat. Spontaneously active units usually possessed nonmonotonic functions with a minimum, and spontaneously inactive units usually possessed monotonic functions or nonmonotonic functions with a maximum (NM+). In response to acoustic high-pass filtered noise, the function relating discharge rate and cut off frequency resembled the same unit's I/O function to electrical stimulation. The I/O functions to acoustic characteristic tones were usually monotonic or NM+. These results suggest that in the DCN, a prerequisite for the generation of acoustic-like responses with an electrical stimulus may be the matching of the cochlear place and spatial extent activated by each stimulus.
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    Prediction of variance in neural response to cochlear implant stimulation and its implications for perception [Abstract]
    O'LEARY, STEPHEN ; Irlicht, Lawrence S. ; BRUCE, IAN ; White, Mark ; Clark, Graeme M. ( 1997)
    Cochlear implant patients' perception of sound is derived via electrical pulses arising from an electrode array. Chosen aspects of the acoustic spectrum are coded via a stimulation pattern designed according to some sound coding algorithm. Thus, a patients' ability to discriminate between sounds, and in turn their understanding, is directly related to their ability to differentiate between the patterns of electrical stimulation which code various sounds.
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    An improved model of electrical stimulation of the auditory nerve
    Bruce, I. ; Irlicht, L. S. ; White, M. ; O'Leary, S. J. ; Dynes, S. ; Javel, E. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Mathematical models are a useful means of formally describing and investigating pertinent features of complex systems such as the human auditory system. These features may be deduced from physiological and psychophysical experiments utilising animal models or humans, and from engineering studies. Historically, models of the auditory nerve's (AN) response to electrical stimulation have ignored randomness in single-fiber activity which has been recorded in physiological studies. These models, however, have been unable to accurately predict a number of important psychophysical phenomena. In this study, a model that incorporates random activity of the AN is presented, and is shown to predict psychophysical performance. These results indicate that random activity is indeed an important part of the response of the AN to electrical stimulation.
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    Responses from single units in the dorsal cochlear nucleus to electrical stimulation of the cochlea
    O'Leary, S. J. ; Tong, Y. C. ; Clark, Graeme M. ( 1992)
    To help improve our understanding of how the brain responds to electrical stimulation of the auditory nerve we have examined the responses of dorsal cochlear nucleus (DCN) units to both acoustic stimulation and electrical stimulation of the cochlea. This work extended our previous studies which have compared the responses to electrical and acoustic stimulation In the auditory nerve (Javel et al 1987, Ann. Otol. Rhinol. laryngeal. Suppl. 128, 96:2630) and the ventral cochlear nucleus (Shepherd et al 1988, NIH Contract NO1-NS-72342, 5th Quarterly Progress Report).