A Brain Chip to Control Paralyzed Limbs

Although their work is in the very early stages, Robert Kirsch and colleagues at the Functional Electrical Stimulation Center are developing a more intuitive way for severely paralyzed individuals to regain motor function.

Scientists are now building a device that records brain signals and transmits them to paralyzed muscles, potentially returning muscle control to severely paralyzed patients. In the prosthetic system, which is still in early development, a brain chip records neural signals from the part of the brain that controls movement. The chip then processes those signals, sending precise messages to wires implanted in different muscles of the patient’s arm or hand, triggering the paralyzed limb to grab a glass or scratch the nose. “Our ultimate goal is for a person to think and effortlessly move the arm ,” says Robert Kirsch , associate director of the Functional Electrical Stimulation Center , at Louis Stokes Veterans Affairs Medical Center, in Cleveland, OH.
But for some patients, especially severely paralyzed individuals with control over few muscles, using signals recorded directly from the brain to control the paralyzed limbs could provide an easier and more intuitive way to move. So the Cleveland researchers are working with John Donoghue , a neuroscientist at Brown University, who has developed implantable brain chips that record and process electrical activity directly from neurons. The device, made by Cyberkinetics Neurotechnology Systems , in Foxborough, MA, consists of a tiny chip containing 100 electrodes that record signals from hundreds of neurons in the motor cortex, the part of the brain that modulates movement. A computer algorithm then translates this complex pattern of activity into a signal used to control a computer or prosthetic limb.
The project is likely to be complex. Donoghue and colleagues must first make their brain chip wireless and fully implantable. (Currently, patients have some hardware protruding from their skull and are connected to a computer via wires.) An implantable system would minimize the risk of infection, and it might also help patients learn to use the system. Eberhard Fetz , a neuroscientist at the University of Washington, in Seattle, who is developing similar systems in monkeys, says that an implantable device would allow patients to use the system 24 hours a day, which would help them learn to modulate neural signals for precise control.

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