The Body Electric

When the organizers of the Fifth Australian Sculpture Triennale in Melbourne asked Australian performance artist Stelarc to submit a proposal for a site-specific installation, he came up with a novel location in which to situate the work: his stomach.

After fasting for eight hours, Stelarc ingested a 15-mm by 5-cm capsule made of titanium, stainless steel, silver and gold. The capsule was tethered to a cable, which was linked to a control box outside his body. The stomach had to be inflated with air before this metallic lozenge slithered its way into Stelarc’s abdomen. Once there, the capsule unfurled to its full dimensions of 5 cm by 7 cm and began beeping and emitting flashes of light.

Stelarc is a living example of the strange and surprising ways technology is getting onto — and under — our skin. Researchers in Europe, America and Japan are implanting electrodes into the bodies of patients to restore vision, treat brain disorders and help victims of paralysis regain motor function, while engineers are creating hybrid prosthetic body parts such as ankles, legs and knees in which silicon chips are melded with living tissue. Computers are moving off the desktop — and making our bodies bionic.

During one 1998 performance, Stelarc wired himself up directly to the Internet. His body was dotted with electrodes — on his deltoids, biceps, flexors, hamstrings and calf muscles — that delivered gentle electric shocks, just enough to nudge the muscles into involuntary contractions. The electrodes were connected to a computer, which was in turn linked via the Internet to computers in Paris, Helsinki and Amsterdam. By pressing various parts of a rendering of a human body on a touch screen, participants at all three sites could make Stelarc do whatever they wished.

Stelarc believes this kind of merger between man and machine will soon make its way from performance art venues into our living rooms. “Just as the Internet provides interactive ways of displaying information,” he says, “it may allow unexpected ways of accessing the body itself. What will be interesting is when we can miniaturize these technologies and implant them directly into the body.”

What Stelarc, who began his career in the 1960s as a “failed painter,” is doing out of artistic choice, Brian Holgersen, a 30-year-old Danish tetraplegic, is doing out of physical necessity. For Holgersen, technology has already become a part of his body. Eight years ago, on a motorcycle trip to the U.K. to visit his sister, he was in an accident and broke his neck. Except for some minor movement in his shoulders, left arm and left hand, he was paralyzed below the neck. Holgersen underwent an experimental surgical procedure to implant a neural prosthesis — an interface between an electronic device and the human nervous system — to bypass the damaged stretches of his spinal cord and restore some movement to his limbs.

Paralysis results from neck and spinal cord injuries because the neural traffic that moves between the brain and the muscles is severed or blocked. Like a kink in a garden hose, spinal trauma cuts off the flow of information that travels along afferent nerves, which send signals from the body to the brain, and efferent nerves, which carry instructions from the brain to the body’s musculature. In many cases of paralysis, though, the motor and sensory nerves below the level of the lesion remain intact and could function again.

To restore basic function to his left arm, Holgersen uses the Freehand System, a device that restores the ability to grasp, hold and release objects. During a seven-hour operation, surgeons at Denmark’s National Hospital made incisions in Holgersen’s upper left arm, forearm and chest. Eight flexible cuff electrodes, each about the size of a small coin, were attached to the muscles in his arm and hand that control grasping. These electrodes were then connected by ultrathin wires to a stimulator — a kind of pacemaker for the nervous system — implanted in his chest. The stimulator was in turn linked to a position-sensing unit attached to Holgersen’s right shoulder, over which he retains some motor control.

When Holgersen wants to pick up a glass, he moves his right shoulder upward. This movement sends an electrical signal from the position sensor, which is worn under his clothing, to the stimulator in his chest, which amplifies it and passes it along to the appropriate muscles in his arm and hand. In response, the muscles contract and his left hand closes. When he wants to release the glass, he moves his right shoulder downward and his left hand opens.

“It’s strange when you first use it,” Holgersen says of the device. “I move my right shoulder and see my left hand move. But I quickly got used to it, and now it feels very natural. I don’t even think about it. It has become part of me and made me more independent.” Thanks to the Freehand implant, Holgersen can now hold a cup, lift a fork and grasp a pen, actions he was previously unable to perform. The Freehand is not for everyone, though. To benefit from the device, patients must have use of a shoulder and upper arm and partial use of their hands. The technology can be fragile, too, and patients must be constantly on guard against infection around the implanted electronics. Another drawback is that the Freehand system provides no tactile feedback for things like temperature, so users also have to be careful when handling hot objects such as cigarettes or coffee. To get around this problem, Thomas Sinkjaer and colleagues at the Center for Sensory-Motor Interaction at Denmark’s Aalborg University are developing neural prosthetics that can actually feel the texture of objects and transmit this information back to the user.

“We want to make patients aware of the parts of their bodies that they cannot sense,” says Sinkjaer, who has worked with Brian Holgersen for the past six years, “and use sensory information from the skin to control the hand automatically as in able-bodied subjects.” This kind of sensitive prosthetic would recruit afferent nerves to send tactile information from paralyzed limbs to other parts of the body, where the sensations could be perceived. With such a device Holgersen might feel the weight of a freshly brewed cup of coffee as a tingling sensation on his cheek; the heavier the cup, the more intense the tingle.

Making this kind of tactile feedback work will be difficult. Hundreds, perhaps thousands, of different nerves would need to be stimulated to create convincing sensations. This is a daunting task, since the hand has the highest density of nerve receptors in the entire body, about 20,000.

Another facet of the bionic future is taking shape in a second-floor laboratory at the University of Louvain in Brussels. There Marie, a 63-year-old Belgian woman, is treated to visions of red, blue and yellow dots arranged in neat little rows like the tops of Lego building blocks. Glimpses of Lego bricks are hardly worth getting excited about, but Marie is enthralled — because she’s blind.

Marie (not this woman’s real name; she wishes to remain anonymous) can see again thanks to an electrode implanted around her right optic nerve. The electrode is connected to a stimulator installed in a small depression carved from the inside of her skull. A video camera, worn on a cap, transmits images in the form of radio signals to the stimulator, which converts these signals into electrical impulses and sends them along Marie’s optic nerve. The optic nerve ferries the signals to Marie’s visual cortex, where they are reassembled into an image: in this case, a collection of red, blue and yellow Lego bricks. “The device is an integral part of my body,” Marie says. “I don’t feel it. I completely ignore it.” Marie is one of only about a dozen people in the world who have had visual implants that could potentially restore their sight.

Marie started to lose her vision when a condition known as retinitis pigmentosa caused the rod and cone cells in her retina to degenerate. When rod and cone cells die off, the retina is rendered insensitive to light and the result is blindness. Marie’s case followed the typical pattern. First her rod cells went, leaving only a slim tunnel of vision through which she could still manage to recognize objects and read with difficulty. But then as her cone cells failed, this last narrow window on the world snapped shut and she was left completely blind — even though her retina retained a healthy connection to the visual centers of her brain through a functioning optic nerve. Marie’s implant splices into the live line of the optic nerve to enable her to see again.

Marie’s artificial visual system is called the Microsystem-based Visual Prosthesis (MIVIP) and was designed by Claude Veraart and collaborators at the University of Louvain. The MIVIP consists of a cuff electrode implanted around Marie’s right optic nerve. The electrode wraps around the optic nerve like the little plastic sheath on the end of a shoelace. It is connected to a thin cable that snakes its way from the optic nerve exiting the back of Marie’s eye and weaves around the outside of her brain to the stimulator implanted in a small cavity in her cranium. The stimulator, which bypasses the damaged rod and cones cells to send electrical signals directly to the optic nerve, is operated by means of radio signals transmitted from the external video camera.

These devices are permanently implanted inside Marie’s skull, but to use them she must travel to a small room at the University of Louvain and don what looks like a badly damaged 1960s bathing cap. The cap is made of plastic and has a standard video camera affixed to its front. To use the MIVIP, Marie sits in front of a large white screen on which an alphabet of about 50 different line configurations is projected.The projected images — an X or an H, for example, or basic forms such as blocks and circles, tables and chairs — contain live pixels that the video camera registers as a flash when it passes over them. As the camera crosses a live pixel, it sends a signal to the transmitter, which passes it on to the stimulator, which sends an electrical charge to Marie’s optic nerve. The result: Marie sees a series of flashes that join up to form recognizable shapes.

Since the camera’s visual range is narrow, Marie has to scan an image by slowly moving her head from left to right and up and down until she’s covered the entire screen. As the camera criss-crosses the visual field, a rapid series of electrical stimulations is sent to her optic nerve. The number of electrical stimulations depends on the number of live pixels on the screen; the more there are, the easier and quicker it is to compile an image. Marie reconstructs the image from what appear to be a series of strobe flashes, an experience that’s a bit like watching a miniature stadium billboard, on which images are also compiled from groups of individual flashing lights.

In the experiments carried out to date, Veraart has noted a correspondence between where Marie sees a flash and that image’s actual location in space, which means that the flashes transmitted to Marie’s optic nerve correlate with the outside world. Veraart has also discovered that different electrical pulses lead to different perceptions. One type of pulse might always produce a yellow image, for example, while another might always produce red. If this turns out to be the case, Veraart and his team intend to compile a lexicon of correspondences so that specific visual stimuli can be easily reproduced. Imagine public spaces seeded with a kind of invisible braille, live pixels embedded in doors, stairways and streetcorners that blind MIVIP users could employ to see important information about their immediate surroundings. Veraart and his colleagues are working to refine the technology so that the blind could actually see obstacles like chairs and tables in this way.

The MIVIP is still a cumbersome and limited device. It hasn’t given Marie her normal vision back. At best, it can help restore mobility by helping people avoid obstacles, recognize landmarks in unfamiliar environments and detect very simple shapes. “This is not true vision,” Veraart stresses. “And it’s definitely not a cure for blindness. It’s something to help people better cope with their impairment. It’s like a wheelchair: it doesn’t help people walk again, but it does help them get around. As a technological solution, that’s not bad at all.” Marie agrees. She has undergone extensive, and dangerous, brain surgery to use the MIVIP and she still shows up every week at Veraart’s lab for more tests and experiments. “Even if I recover only light and shadows,” she says, “it would still be worth it.”

Computer pioneer Norbert Wiener once advised, “Render unto man the things which are man’s and unto the computer the things which are the computer’s.” As the experiences of people like Stelarc, Brian Holgersen and Marie show, it’s becoming increasingly difficult to tell the difference.

James Geary 2002. This is an edited excerpt from Geary’s book The Body Electric: An Anatomy of the New Bionic Senses, published in the U.K. by Weidenfeld & Nicolson