I'm sitting at a table draped in black, surrounded by black curtains. Candles, spheres, and unfamiliar symbols have been placed before me. My right hand, arms, and head are strapped with wires, and my mouth is filled with electrodes. I'm blindfolded.
Although this may sound like a scene for a Black Mass, it's even stranger than that: I'm trying to see with my tongue.
The gear I'm wearing was invented by Paul Bach-y-Rita, a neuroscientist at the University of Wisconsin at Madison. Bach-y-Rita has devoted much of his career to a single, revolutionary concept: that our senses are interchangeable. The brain, Bach-y-Rita and many other neuroscientists believe, is an organ of astonishing plasticity: If one part of it is damaged, another part can serve the same function. To prove the point, his collaborator Kathi Kamm, a professor of occupational therapy at the university's Milwaukee campus, has strapped a small video camera to my forehead and connected it to a long plastic strip hanging from my mouth. A laptop computer reduces the camera's image to 144 pixels. Those pixels are converted to an electric current that is sent to the business end of the plastic strip — a 12-by-12 grid of electrodes that rests on my tongue.
Kamm sits down in front of me. She says she's holding a ball, but I can't hear a sound as she rolls it back and forth over the cloth-covered table. She says the ball will soon be rolling toward me — to my left, my right, or straight at me — but my eyes and ears have no way to tell where it's going.
That leaves my tongue. It has more tactile nerve endings than any part of the body other than the lips. What the camera sees is zapped onto my tongue's wet, conductive surface. As Kamm rolls the ball, my blindfolded eyes see nothing, but a tingling passes over my tongue. When she sends the ball my way, my hand leaps out to the left.
