Robert K. Shepherd
B.Sc. (Deakin), Dip. Ed (Hawthorn), Ph.D. (Melbourne)

Director of The Bionic Ear Institute
Professor of Medical Bionics, University of Melbourne

The Bionic Ear Institute
384-388 Albert Street
East Melbourne VIC 3002
Australia
Ph:  +61 3 9667 7513
Fax: +61 3 9667 7518
E-mail: rshepherd@bionicear.org

I have been actively involved in cochlear implant research in the Department of Otolaryngology since 1980. In the ‘80s my major research interests were focused on safety issues associated with cochlear implants, with particular emphasis on the Nucleus® multiple-electrode cochlear implant system. My major research interests included materials biocompatibility, electrode design, electrode insertion trauma, chronic electrical stimulation safety studies, and corrosion of platinum electrodes following long-term use.

In the late ‘80s my interests turned to safety issues particularly associated with cochlear implants in children. This work was principally funded from an NIH contract (Graeme Clark, P.I), and enabled our safety studies to expand to include issues of skull growth, surgical and implant design considerations for very young children, effects of electrical stimulation on the developing auditory pathway, and safety issues associated with cochlear implantation and otitis media. Important research outcomes from this work in terms of my current research interests included the development of safe and effective deafening techniques in the developing auditory system, and evidence that chronic electrical stimulation can at least partially reverse the atrophic changes that occur within the central auditory pathway following a sensorineural hearing loss.

My current research can be divided into two major areas of interest. First, the physiological and morphological response of the central auditory pathway to a sensorineural hearing loss. This work, which has been performed with Natalie Rickard, Tony Paolini, Lloyd Roberts as well as collaborative links with scientists from the J. W. Goethe-Universitt, Frankfurt, the University of Minnesota, Minneapolis, Blodell Hearing Research Center, University of Washington, Seattle and Department of Otolaryngology, Johns Hopkins University Baltimore. Our research has shown that many of the basic response properties at the level of the auditory nerve, auditory midbrain and auditory coretex - including tonotopic organization - show little change with hearing loss. There is, however, evidence of significant reduction in the temporal processing ability of auditory neve and auditory midbrain neurones in neonatally deafened animals. Moreover, significant morphological changes also occur in response to a sensorineural hearing loss, including a significant reduction in the volume and a significant increase in neural packing density of the cochlear nucleus, and a significant decrease in the synaptic density of neurones within the auditory midbrain. This work, which has been largely funded by the Garnett Passe and Rodney Williams Memorial Foundation, is expanding to investigate the effects of "re-afferentation" of a silenced auditory pathway using electrical stimulation o f the auditory nerve via a cochlear implant. This new phase of research has been funded from an NIH contract (Robert Shepherd, P. I.). More recently we have combined the effects of electrical stimulation with exogenous delivery of neurotrophins in order to study auditory nerve rescue following a sensorinual hearing loss. This work has been performed in collaboration with Anne Coco, Stephanie Epp, Sarah McGuinness and other colleagues at the BEI. Our current NIH Contract will provide an update of research in this area together with our central plasticity studies

My second major research interest is associated with safety issues in cochlear implants. This work is performed with Peter Seligman and colleagues from the CRC and Cochlear Limited. This work is principally concerned with an investigation of stimulus induced neural damage mechanisms, the development of protocols for safe electrical stimulation of the auditory nerve, and techniques designed to minimise direct current and the production of adverse electrochemical by-products.

Interested graduate students are encourage to email me if you have an interest in perusing a higher degree in any aspect of the research described above

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  Author: rshepherd@bionicear.org    Last Updated:  Tuesday July 29 2008