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Scientists in the US have shown that "electrocorticographic" signals from the brain can be used to manipulate an external device. The techniques developed by Daniel Moran of Washington University in St Louis, Eric Leuthardt from the Barnes-Jewish Hospital, also in St Louis, and colleagues could ultimately lead to artificial limbs that can be controlled by thought alone (E C Leuthardt et al. 2004 J. Neural Eng. 1 63). From studies
on animals scientists know that specific nerve cells become active just
before the animal makes a certain movement. By processing the electric
signals from these cells it is possible to predict the movement before
it is actually made. The same information could also be used to make an
artificial limb perform the same movement. Moran and colleagues measure the neuronal signals by placing a grid of electrodes directly on the surface of the brain (figure 1). This method, which is known as electrocorticography (ECoG), is routinely used to monitor and control seizures in patients with epilepsy. It provides much better signals than electroencephalography, in which the electrodes are placed on the scalp, and is much less traumatic than procedures in which the electrodes actually penetrate the brain. Leuthardt,
Moran and co-workers asked four volunteers -- who were already wearing
the electrodes -- to perform certain movements that included opening and
closing their hands and sticking out their tongue. During this time, the
scientists identified which brain signals were associated with each of
the different movements. Next, the patients were asked to attempt to control a cursor on a computer screen by imagining to make these movements. This part of the research relied on a computer program called BCI2000 that had been developed by team member Gerwin Schalk at the Wadsworth Center in New York. After just a few minutes of training, the patients were able to control the cursor using their thoughts with an accuracy of over 70%. "The
ability to operate a prosthetic device using the electric signal of the
brain is rapidly leaving the realm of science fiction and becoming a realistic
goal of the scientific community," Leuthardt told PhysicsWeb. "Our
research could ultimately be used as a tool for people with severe motor
disability. It could allow them to better interact with the world through
devices that are controlled by thought alone and do not require the use
of peripheral nerves or muscles." Belle Dumé is Science Writer at PhysicsWeb SOURCE: www.physicsweb.org More headlines at www.mindpowernews.com
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