Graeme Clark Collection

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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. (Karger, 1993)
    An aim of the electrical stimulation strategy of a cochlear implant is to mimic the response of the auditory system to acoustic stimuli, so that hearing sensations generated by the implant can be recognisable and useful to the implantee. 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 and electrical stimulation of the cochlea in a hearing animal. This work extended our previous studies which have compared the responses to electrical and acoustic stimulation in the auditory nerve [1] and the ventral cochlear nucleus [2]. Our studies addressed two questions: (1) What are the responses of DCN units to electrical stimulation of the auditory nerve? (2) Was it possible to identify acoustic and electrical stimuli which generated similar responses from individual DCN units? By answering questions 1 and 2, it may be possible to deduce the electrical stimulus parameters which should be employed in cochlear implant speech processing strategies to mimic acoustic-like responses from neurons of the dorsal cochlear nucleus. The generality of observations from the cochlear nucleus could then be tested at other nuclei within the central auditory pathways.
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    Three-dimensional reconstruction of the cochlea and temporal bone
    Dahm, Markus C. ; Seldon, H. Lee ; Pyman, Brian C. ; Laszig, Roland ; Lehnhardt, Ernst ; Clark, Graeme M. (Karger, 1993)
    In recent years, cochlear implantation has become an established method for the auditory rehabilitation of profoundly deaf patients and is used in ever more and younger patients. High-resolution computed tomography is performed routinely on all prospective cochlear implant patients and provides important information about cochlear or mastoid pathology that will enable the surgeon to select a side for operation and alert him to surgical obstacles he might encounter [1-4]. In analysing the CT films he must still try to form a three-dimensional image in his mind by looking through a large number of different pictures [5]. Consequently, to make it easier to understand, we applied our own image analysis system to produce three-dimensional reconstructions of temporal bones from CT scans[6]. We focused on the use of this method for the preoperative examination and surgical planning for cochlear implantation as well as for our research purposes. This system and the results are presented here.