A multiple electrode cochlear implant

Abstract

The University of Melbourne Departments of Otolaryngology and Electrical Engineering (UMDOLEE) receiving and stimulating component of a multiple-electrode cochlear implant hearing prosthesis produces constant stimulation. It has a stimulating pulse shape that minimizes the production of toxic substances and loss of metal from the electrodes, and this is achieved with a biphasic rectangular waveform where the first phase is negative with respect to ground. The duration of each stimulus phase in 180 msec, which is long enough to allow low levels of current stimulation, and short enough to permit rates of 1000 pulses/second to be achieved. In order to be consistent with our present understanding of the perception of pitch, the device permits the independent stimulation of a number of electrodes. Furthermore, to electrically isolate the stimulus to small areas, there is the capacity to vary the current and set the threshold independently at individual electrodes. The phase and amplitude of the pulses to neighbouring electrodes with also be varied to assist in localizing the current flow. The pattern to stimulation to individual or groups of electrodes can also be altered to enable studies to be carried out to determine ways of conveying frequency and intensity information over a more normal dynamic range.

A lithographically-patterned, elastic multi-electrode array for surface stimulation of the spinal cord

“…Clinical advancements made possible by NP technology include those that restore hearing (Clark et al, 1977;Kessler, 1999;Spelman, 1999), respiration (DiMarco, 2001), bladder voiding (Brindley et al, 1982;Grill et al, 2001), and upper and lower extremity control (Kraft et al, 1992;Kralj et al, 1988;Liberson et al, 1961;Prochazka et al, 1997;Taylor et al, 1999;Weingarden et al, 1998). A subset of these prostheses communicates with neural tissue via penetrating multiple-electrode arrays (MEAs), which can provide highly specific and robust activation of the targeted neurons (Branner et al, 2001;Hillman et al, 2003;McDonnall et al, 2004;Tyler and Durand, 2002).…”

Personal reflections on the multichannel cochlear implant and a view of the future

“…Furthermore, later results confirmed that patients with implants were unable to discriminate differences in rate ≥200 to 700 Hz [7][8][27][28][29]. Field potentials from superior olivary complex in auditory brainstem of cat for 1 and 300 pps rates of simulation of auditory nerve in cochlea.…”

“…A connector was used initially but was later found to be unnecessary if a failure occurred, because the banded electrode array could easily be slipped out and another inserted [59]. The principles underlying the electronic design of the Melbourne receiver-stimulator were elaborated in an article in 1977 [85] and a provisional patent filed in 1976 [83]. The amplitude, rate, and timing of biphasic pulses on each of 10 to 15 channels were independently controlled to stimulate an electrode array passed around the basal turn of the cochlea.…”

“…If pitch was perceived, the auditory nerve was considered intact [85]. A protocol was established for minimizing any risk of introducing infection during surgery [86].…”

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“…With rate of stimulation on each electrode he could distinguish pitch, but only up to 300 Hz, as shown in Figure 15 (Clark et al 1978;Tong et al 1982). This figure shows the pitch ratio versus repetition rate reached a plateau at 300 Hz.…”