Bionic Hardware

In her influential essay "A Cyborg Manifesto," science historian Donna
Haraway suggests that the severely disabled are often the first to
appreciate the fruitful couplings of humans and machines. A brief
conversation with anyone who has a pacemaker, a new hip, a (good) hearing
aid, an artificial heart, or any one of a host of bionic devices will bear
this out.

The neural prosthetic and interface technologies of today can be broken
down into three major areas: auditory and visual prosthesis, functional
neuromuscular stimulation (FNS), and prosthetic limb control via implanted
neural interfaces. So far, the most successful implants have been in the
realm of hearing. Larry Orloff, a scientist who had suffered hearing loss
since childhood, edits Contact, a newsletter for people with hearing
implants. He reports that there are more than 7,000 people worldwide
outfitted with cochlear implants. These devices work through tiny
electrodes placed in the cochlea region of the inner ear to compensate for
the lack of cochlear hair cells, which transduce sound waves into
bioelectrical impulses in ears that function normally. Although current
versions of these devices may not match the fidelity of normal ears, they
have proven very useful. Dr. Terry Hambrecht, a chief researcher in neural
prosthetics, reports in the Annual Review of Biophysics and Bioengineering
(1979) that implanted patients had "significantly higher scores on tests
of lipreading and recognition of environmental sounds, as well as
increased intelligibility of some of the subjects' speech."

The hearing-implant patients and family members I interviewed spoke of
their desperation during their deaf years and emphasized how much they
appreciated the technology that had changed their lives. John Anderson, a
43-year-old implant recipient from Massachusetts offered his views via
electronic mail (he still has trouble communicating by phone): "The
silence of those three years when I was totally deaf is still deafening to
me these many years later. My life was in the hearing world and it was
critical for me to be able to hear like 'everyone else.'" Orloff spoke
movingly of hearing things like crickets, birds, and church bells for the
first time. He also points out that computer networking was instrumental
in his getting the implant: He first learned of the technology on
CompuServe.

An even more radical type of auditory prosthesis now under development
snakes hair-thin wires deep into the brain stem, linking it with an
external speech processor. But don't expect to see it soon.

Visual prosthetics is still a long way from offering any major
breakthroughs, though several promising directions are being explored. The
goal of most of these schemes is to implant electrodes into the visual
cortex of the brain to stimulate discernible patterns of phosphenes which
can then be interpreted by the user. Phosphenes are those tiny dots (the
proverbial stars) that can be seen after rubbing one's eyes or after
getting beaned on the head. These phospenes originate in the brain and are
responsive to electrocortical stimulation. Recently, Dr. Hambrecht and
fellow researchers at the National Institutes of Health (NIH) implanted a
38-electrode array into the visual cortex of a blind woman's brain. She
was able to see simple light patterns and to make out crude letters when
the electrodes were stimulated.

Richard Alan Normann, professor of bioengineering at the University of
Utah, has been developing similar "artificial eyes" that would use denser
phosphene arrays (100 electrodes). The long-range goal of his research is
the development of vision hardware that "will consist of a miniature video
camera mounted on a pair of sunglasses, signal processing electronics, a
transdermal connector to pass across the skin, and an array
of...microelectrodes permanently implanted in the visual cortex." The
development timetable for these systems is still long-term; advances have
been slow. Often years pass between experiments as researchers
painstakingly assemble the required miniature electronics.

Beyond sight and sound, functional neuromuscular stimulation systems are
in experimental use in cases where spinal cord damage or a stroke has
severed the link between the brain and the peripheral nervous system.
These systems usually combine implanted electrodes and an external
battery-powered microprocessor. The system is controlled by switches,
either triggered manually or through movement of some body part (an elbow
or shoulder) that is still operational. These types of systems are likely
to be used clinically one day to restore movement in legs, arms, and
hands. Similar electrical stimulation schemes to restore bladder control
and respiratory functions are also in experimental and even clinical use.

Some of the most compelling research in the area of neural interfacing is
being done at Stanford University. A recent article in the IEEE
Transactions on Biomedical Engineering (V39, N9) reports that "a
microelectrode array capable of recording from and stimulating peripheral
nerves at prolonged intervals after surgical implantation has been
demonstrated." These tiny silicon-based arrays were implanted into the
peroneal nerves of rats and remained operative for up to 13 months. The
ingeniously designed chip is placed in the pathway of the surgically
severed nerve. The regenerating nerve grows through a matrix of holes in
the chip, while the regenerating tissue surrounding it anchors the device
in place. Although this research is very preliminary and there are still
many intimidating technical and biological hurdles (on-board signal
processing, radio transmittability, learning how to translate neuronal
communications), the long-term future of this technology is exciting.
Within several decades, "active" versions of these chips could provide a
direct neural interface with prosthetic limbs, and by extension, a direct
human-computer interface.

While a composite image of all these technologies might portray the bionic
humans of SF, the practical limitations and technological obstacles are
still sobering. Very few of these technologies are in approved clinical
use, and most of them will not be for a decade or two. One of the main
things frustrating this research is finding (or developing) materials that
are not toxic to the organism and that will not be degraded by the
organism. The human body has formidable defenses against invading hardware.

Besides the material and physical hurdles, this technology raises
tremendous ethical and social issues. Many critics say that neural
implants are impractical at best, if not downright irresponsible. These
critics contend that implants are bioengineering marvels looking for a
justifiable use, rather than appropriate technology for the disabled.
Other naysayers argue that these unproven prosthetic devices give
experimental subjects unreasonable expectations of sight, sound, and
independence. Scott Bally, assistant professor of audiology at Gallaudet
University, points out that auditory implants are very controversial in
the deaf community. "Many deaf people feel as though deafness is not a
handicap. They are culturally deaf individuals who have successfully
adapted themselves to being deaf and feel as though things like cochlear
implants would take them out of their deaf culture, a culture which
provides a significant degree of support."

William Sauter, head of prosthetics at MacMillian Medical Center in
Toronto, also has reservations. "A patient must go into surgery again, and
I think most amputees don't like to be opened up," he observes in a May
1990 Science article on the Stanford research. In thinking of a future
populated by machine-grafted humans, questions are raised as to how
society as a whole will relate to people walking around with plugs and
wires sprouting out of their heads. And who will decide which segments of
the society become the wire-heads? "People are just not ready for
cyborgs," says the implanted John Anderson.

And the moral issue of animal testing cannot be overlooked. Society as a
whole, and armchair "neuronauts" in particular, should be aware that this
research is totally dependent on the extensive use of laboratory animals.
Legions of cats, monkeys, rats, rabbits, bullfrogs, and guinea pigs have
been poked, prodded, zapped, and stuffed full of experimental hardware in
the name of progress.