Shattered Nerves: How Science Is Solving Modern Medicine's Most Perplexing Problem

4 The Grandfather of Neural Prostheses

∑ 4 The Grandfather of Neural Prostheses An often-told tale about Giles Brindley might reveal something about the person referred to as the grandfather of neural prostheses. In 1983, the inveterate innovator and self-experimenter stood before a scientific audience and removed his pants. The venue was Las Vegas, Nevada, and the audience that witnessed this occurrence was the membership of the American Urological Association. Brindley was demonstrating, quite graphically, the success of an injection of phenoxybenzamine, a treatment he had developed for erectile dysfunction. ‘‘The drug is very long acting and I injected it before the meeting. I wasn’t intending to show it,’’ said Brindley, ‘‘except the chairman asked me to, so I asked the audience if they had any objection and the audience didn’t have any objection. I said, ‘Well alright,’ and I showed it.’’ Though this has nothing to do directly with neural prostheses, it shows what a unique and dynamic individual Brindley is. Born on April 30, 1926, in Woking, England, Brindley single-handedly invented an eighty-oneelectrode prosthesis that in 1967 he and surgeon Walpole Lewin implanted on the visual cortex of a blind nurse, which succeeded in causing her to see spots of light. At the same time, he was busily at work on neural prostheses that were successfully implanted in a number of paralyzed patients to help them move their arms, stand, walk, and even pedal a bicycle. Brindley is also the inventor of a bladder and bowel stimulator that allows paralyzed individ- 56 Shattered Nerves uals to void more normally and in some cases have erections as well. This neural prosthetic device is commercially available and has been implanted in thousands of individuals worldwide. He is also the founder of the Neurological Prosthesis Unit of Britain’s Medical Research Council. A man of insatiable curiosity, in addition to pioneering the development of numerous neural prosthetic implants, Brindley has conducted many dramatic experiments on his own body. One such experiment was inspired by the fact that birds are known to have color filters in front of their retinas and humans do not. This led Brindley to wonder whether various wavelengths of light would be perceived di√erently from behind the eye than they are from the front. And what better way to answer that question, he reasoned, than to shine various colors of light onto the back of his own eyeball? Asked if this required removing his eyeball from its socket, he laughingly replied, ‘‘Oh, no. You don’t need to do that. You only need to turn the eye as far to one side as it will go, and put a light guide into the conjunctival sac—the sac separating the eyelid from the eye, into which tears flow—you can get the light ’round to the back of the eye. No open surgery was required,’’ he said. ‘‘For the first trial, I used an auriscope light, which is a tiny electric light bulb at the end of a rather long stem. I anesthetized the conjunctival sac because it is a bit painful to put an electric light bulb into your conjunctival sac, and then turned the eye right around, put the thing into the sac, and pushed it against the globe, and switched the light on. I could see it immediately , not where it physically was but projected out into space,’’ Brindley said. ‘‘To test whether colors looked the same whether the light reached the rods and cones from in front or behind, I had to replace the auriscope bulb by a glass light-guide, and get the light from a prism spectrometer or from a gas discharge tube with color filters to isolate single spectral lines. The answer was that light of any one wavelength looked very nearly the same color, whether it came from behind or in front of the retina.’’ In that experiment, conducted in 1959, he needed to turn his eye only as far as he could do so voluntarily. In yet another visual experiment conducted the following year, however, he pushed things a bit further. This time, he wanted to learn about the position-sensing ability of the eye. To do so, he enlisted the help of a colleague, Patrick Merton, who, after anesthetizing The Grandfather of Neural Prostheses 57 Brindley’s conjunctival sac, actually seized the eyeball with a forceps. ‘‘When he grasped my eye with forceps and pulled it about...