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4. Brain-Machine Interfaces
Not only can our brain be manipulated by machines, our brain can also control machines. One of the applications of brain-machine interfaces is aiding patients locked into paralysis by enabling them to convey their thoughts and feelings directly from the brain to a computer screen. How this is accomplished is as follows: electroencephalographic electrodes can detect brain waves, which can then be transmitted to a machine for performing some desired action (see Figure 4).
Figure 4: Connecting brains with computers.
Brain-machine interfacing was initiated in 1963 by roboticist William Grey Walter, who handed fake remote controls to his experimental subjects for advancing slides one by one on a slide projector. The patients were startled to see the slide advance just before they were about to push the button. Unkown to the patients, the projector was advanced every time the electrodes in their motor cortices picked up brain signals and transmitted them to the projector. This early experiment demonstrated that humans can control machines soleley with brain signals .
The Thought Translation Device allowed completely paralyzed patients to write with their brains.This has led neuroresearchers to devise electroencephalographic electrode implants as clinical remedies of neurophysical diseases. University of Tubingen professor Niels Birbaumer won the 1995 Leibniz Prize for formulating a neurofeedback therapy to enable epileptics to thwart their seizures. He also invented the "Thought Translation Device," which allowed completely paralyzed patients to write with their brains.One of Birbaumer's patients suffered from amyotrophic lateral sclerosis, Lou Gehrig's disease in which motor tract tissue thickens in the lateral columns and anterior horns of the spinal cord, resulting in progressive muscle atrophy. The patient even lost control over the blinking of his eyes. After repeated training, the patient was able to respond to questions and write his name with the Thought Translation Device. Thus Birbaumer achieved what no other neuroscientist had before him - a method of communication for a thoroughly paralyzed patient .
Apart from inventing communication channels for the completely paralyzed, researchers have also demonstrated by experimenting on animals how artificial limbs might be controlled by motion-impaired patients just with their thought processes. Researchers at Duke discovered that rats can manipulate a computerized lever just with their brain. The rats had learned to press a robotic lever to obtain water, and whenever they would do so, a certain pattern of brain signals was detected by electrodes implanted in the rats' brains. In a "neurorobotic" mode, the robotic lever was activated not by its being pressed but only whenever the same pattern of brain signals was detected by the brain electrode implants. After repeated training in this "neurorobotic" mode, rats were able to control the robotic lever just with their mind, without having to press it manually .
Not only rats, but also monkeys have been trained in controlling a robot solely mentally. A tiny owl monkey in a soundproof chamber at a Duke University laboratory, was trained to move a joystick to follow a horizontal series of lights on a display panel. An array of microwires was implanted into the monkey's motor cortex, the nerve tissue that transmits neural signals to spinal nerve cells for enabling limb movement.The monkey's arm and the robot arms moved synchronously, all three of them controlled by the electrical patterns of the animal's brain.Electrical patterns detected in the motor neurons were transmitted to a local and remote computer. Real-time mathematical models converted the pattern of action potentials produced by the motor neurons into instructions commanding two robot arms, one locally at Duke and another remotely over the Internet, miles away at Massachusetts Institute of Technology. The monkey's motor neuronal patterns were rendered into automaton instructions in the same time period it takes for the motor cortex to direct muscle movements, i.e. 300 milliseconds. The monkey's arm and the robot arms moved synchronously, all three of them controlled by the electrical patterns of the animal's brain . All this magic was possible due to neuroelectronic circuits reading, processing, and transmitting the monkey's brain waves.
Converting electrical patterns in a brain into robotic motion gives way to mental control of computerized limbs that can greatly facilitate locked-in patients, amputees, and the handicapped or disabled. A quadriplegic at Ohio's MetroHealth Medical Center, in an unprecedented experiment directed by neuroscientists of Case Western Reserve University, was able to control his hand just by thinking about it. Previously, the patient had to shrug his shoulder to initiate a commercial FES (functional electrical stimulation) system, comprising of subcutaneous electrodes implanted in his muscles, which allowed him to manage hand motions. However, the Cleveland team obviated the shoulder shrug and empowered the patient to manipulate his hand motions directly from the brain, by detecting and interpreting his brain waves. Thus, they established a synthetic link between the patient's motor cortex and muscles .