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Kennedy, who invented the subcranial cortical implant used in these operations, wanted to create a device that could acquire a signal from inside the brain - a signal robust enough to travel through wires and manipulate objects in the physical world. Making this happen involved creating new access points for the brain, in addition to the natural ones (defunct in Ray's case) that produce muscle motion. Bakay has since moved to Rush-Presbyterian-St. Luke's Medical Center in Chicago, where he is part of an institute devoted entirely to alternative brain-body interfaces.
"We simply make a hole in the skull right above the ear, near the back end of the motor cortex, secure our electrodes and other hardware to the bone so they don't migrate, and wait for a signal," Bakay says. The implant is an intriguing hybrid of electronics and biology - it physically melds with the brain tissue.
"We use a small piece of glass shaped like two narrow cones into which a gold electrical contact has been glued," Bakay says. "The space in the cones is filled with special tissue culture, and the whole thing is placed inside the motor cortex." The tissue culture is designed to "attract" brain cells to grow toward the contact. When brain cells meet gold, the electrical activity of individual cells is detectable across the electrode. Gold wires carry signals back out of the skull, where they are amplified. This produces a far more sensitive and usable signal than you get from surface technology like the taped-on electrodes used in EEGs.
To get a broad sense of what the patient's brain is doing, neurologists perform magnetic resonance imaging and compare changes in the motor cortex with voltages monitored through electrodes. Then the doctors get really clever. The patient is encouraged to think simple thoughts that correspond to distinct conditions and movements, like hot/cold or up/down. Gradually, the doctors extract and codify electrical patterns that change as as a patient's thoughts change. If a patient can reproduce and trigger the signal using the same thought patterns, that signal can be identified and used to control, say, a cursor on a computer screen. The technique is very crude, but what Bakay and his colleagues have demonstrated is a truely alternative brain-body interface platform.
Ray's implant was installed in 1998, and he survived to start working with the signals, which were amplified and converted to USB input for a Dell Pentium box.
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A pioneering group of neuroscientists affiliated with Emory University in Atlanta have conducted a series of animal and human experiments dating back to 1990, Philip Kennedy, Roy Bakay, and a team of researchers have created an alternate interface for the brain, that is, an interface other than the human body. This new interface is created using electrodes surgically implanted in the brain. In 1996, their success with primates convinced the FDA to allow two human tests. The first subject, whose name was withheld to protect her privacy, was a woman in the terminal stages of ALS (Lou Gehrig's Disease); she died two months after the procedure. The second was Johnny Ray.