Experimental visual prosthesis

Donaldson, P. E. K.

doi:10.1049/piee.1973.0061

Cited by 31 publications

(18 citation statements)

References 5 publications

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“…They also understood the possi4ility of unpredictable side effects of prolonged stimulation, although such risks were thought to be small because of experience with our series (3,7) and particularly Brindley's subjects (2,(4)(5)(6). Both patients realized that such experiments might eventually lead to a useful device, but had no illusions that their participation would directly benefit them in the immediate future.…”

mentioning

confidence: 96%

“…However, we believe that the difficulties with movement are restricted to our percutaneous electrode arrays. This should not be a problem in a permanent implant, as judged from the stability of the array (12) in Brindley's first patient for 6 years.…”

mentioning

confidence: 99%

“…The saturation density nj* is simply the limit of n, as t -* o0, so that 00 ni= * f Fvidt = (Ir/4)½V2(FI/v)½)" (6) 0 Thus k, in Eq. 1 equals (7r/4)% -0.886, which is in good agreement with Glass's computer estimate (2).…”

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confidence: 99%

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Artificial Vision for the Blind: Electrical Stimulation of Visual Cortex Offers Hope for a Functional Prosthesis

Dobelle

Mladejovsky

Girvin

1974

Science

403

178

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Electrical stimulation of the occipital cortex resulted in discrete photic sensations or "phosphenes" in two volunteers who had been totally blind for 7 and 28 years, respectively. Stimulation of multiple electrodes allowed one patient to recognize simple patterns, including letters. Both patients made an uneventful recovery, and the success of these experiments reinforces the hope that a functional visual prosthesis can be developed, although many problems remain to be solved.

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confidence: 96%

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confidence: 99%

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Artificial Vision for the Blind: Electrical Stimulation of Visual Cortex Offers Hope for a Functional Prosthesis

Dobelle

Mladejovsky

Girvin

1974

Science

403

178

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“…• Then lump together the three capacitances in tubes [1][2][3][4][5][6] and call them C ΣΔWS , C ΣΔWC and C ΣΔCS . That gives the double delta model shown in figure 16(a).…”

Section: High-frequency Asymptotementioning

confidence: 99%

Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces

et al. 2018

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Objective. Neural interfaces and other implantable micro-devices that use polymerencapsulated integrated circuits will only be allowed in medical devices when their lifetimes can be estimated from experimental data. An apparatus has been developed and tested that allows hundreds of insulated samples (interdigitated combs) to be aged under accelerated conditions of high temperature and voltage stress. Occasionally, aging is paused while the sample's impedance is measured; the impedance spectrogram may show degradation as it progresses before failure. Approach. The design was based on practical considerations which are reviewed. A Solartron Modulab provides the frequency response analyser and the femtoammeter. The apparatus can accommodate batches of samples at several temperatures and with different aging voltage waveforms. It is important to understand features of the spectra that are not due to comb-comb leakage, but come from other places (for example substrate-solution leakage); some have been observed and investigated using SPICE. Main results. The design is described in detail and test results show that it is capable of making measurements over long periods, at least up to 67 °C. Despite the size of the apparatus, background capacitance is about 1 pF and comb-comb capacitances of about 30 pF can be measured down to 10 mHz, an impedance of about 100 GΩ. An important discovery was the advantage of grounding the bathing solution, primarily in that it raises the measurement ceiling. Observation and SPICE simulation shows that leakage from the substrate to the bathing solution can give phase lags >90°, in contrast to comb-comb leakage which reduces phase lag to <90°. Significance. The value of this paper is that it will facilitate research into the endurance of small implanted devices because, given a description of a proven apparatus, researchers can start building their own apparatus relatively quickly and with confidence.

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“…A number of other publications by Brindley and his colleagues verified these original preliminary observations, examined the stability of phosphenes over time, examined the specific visuotopic representation of the phosphenes, and discussed the various methods of mapping phosphene space. 15 " 21 Some of the above observations were made on a 64-year-old man who had been blind for 30 years who received an implant in 1972 over both occipital lobes. 16 The phosphenes in this second patient were large and hence not easily usable.…”

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confidence: 99%

Current Status of Artificial Vision by Electrocortical Stimulation

Girvin

1988

Can. j. neurol. sci.

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ABSTRACT:The history of the provision of artificial vision by electrocortical stimulation has its origin in observations over 50 years ago. However, the realistic modern stimulation of human visual cortex is only 20-years-old. No useful device has been devised as yet and it therefore remains purely experimental. The primary objective of such a prosthetic device is that of independent mobility. This would require the appreciation of half-tone pictures, the detection of depth and discontinuities in outlines, and a significant quality of resolution. Some of the problems which threaten resolution in such a device and the factors which must be overcome in order to achieve a useful visual prosthesis are discussed. RESUME: Mise a jour sur la vision artificielle par stimulation electrocorticale. L'historique de la vision artificielle par stimulation eiectrocorticale tire son origine d'observations faites il y a plus de cinquante ans. Cependant, l'approche moderne de stimulation du cortex visuel humain a seulement vingt ans. Aucun appareil efficace n'a encore 6t6 invents et ce proc£de" demeure purement experimental. L'objectif principal d'une telle prothese est la mobility autonome. Pour atteindre ce but, le prothese doit fournir une appreciation des demi-tons, de la profondeur et des interruptions dans le contour des objets ainsi qu'une resolution de bonne qualite. Nous discutons de quelques uns des problemes qui ont trait a la resolution dans ce type d'appareil et des obstacles qui doivent etre contournes pour arriver a realiser une prothese visuelle efficace.

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Experimental visual prosthesis

Cited by 31 publications

References 5 publications

Artificial Vision for the Blind: Electrical Stimulation of Visual Cortex Offers Hope for a Functional Prosthesis

Artificial Vision for the Blind: Electrical Stimulation of Visual Cortex Offers Hope for a Functional Prosthesis

Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces

Current Status of Artificial Vision by Electrocortical Stimulation

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