When a person with paralysis imagines hard enough action to move a limb, there are cells in the part of the brain that controls movement, still activated as if trying to make the limb immobile realizes planned movement, although neurological disease or injury has cut the communication between brain and muscles in many cases the region where the signals originate remains intact and functional.
In recent years, neuroscientists and neuroengineering have begun to develop implantable sensors that can measure brain signals of individual neurons. These signals, after applying a mathematical algorithm decoding, can be used to control a cursor with thoughts shown on a computer screen. Such devices are based on neural prostheses.
A team of researchers from Stanford University in California has developed an algorithm, known as REFIT, which greatly improves the speed and accuracy of neural prostheses used to control a cursor on a computer screen.
In rhesus monkeys demonstrations, the efficiency achieved with cursors controlled through the algorithm doubled refit of existing systems and approached that of a real arm. Even more than four years after its introduction in the first animals, the new system is still going strong, whereas previous systems have seen a gradual decline in efficiency as time has passed.
The system developed by the team of Krishna Shenoy, professor of electrical engineering, bioengineering and neurobiology at Stanford University, is based on a silicon chip implanted in the brain, which records what is known as “action potentials”, in neural activity captured by a series of electrodes, and sends data to a computer. The frequency at which action potentials generated provides key information to the computer about the direction and speed of movement to the user wishes.
In the research and development have been also participated by Vikash Gilja, Paul Nuyujukian, Cynthia Chestek, John Cunningham, Byron Yu, Joline Fan, Mark Churchland, Matthew Kaufman, Jonathan Kao, and Stephen Ryu. There are among the organizations that have funded the project, included the Christopher and Dana Reeve Foundation for the Study of Paralysis.