by Karla Gale

NEW YORK (Reuters Health) Jul 12 - A paralyzed patient's brain activity can be harnessed through a brain-computer link to direct movements and restore lost motor function, according to two pilot studies reported in the July 13th issue of Nature.

"What is currently available to paralyzed patients is an eye tracker mounted on the headband or wheelchair, which optically looks at the eye, determine where it is pointing, and uses that to control cursor on screen," Dr Krishna V. Shenoy, co-author of one of the papers, said in an interview with Reuters Health. "But this modality is bulky and commandeers eye movement."

"Our goal is to couple natural intention to move with tools that will provide interaction with the patient's environment," continued Dr Shenoy of the Stanford University School of Medicine in California. He believes the neuromotor systems described in the Nature papers will become widespread in clinical practice, like cochlear implants for hearing loss and deep brain stimulation for Parkinson's disease.

"Our research has been invigorated by the microelectronics industry that gave us the ability to build complicated electronic systems that move fast," he added, "as well as advancements in the field of neuroscience."

In another paper by Dr John P. Donoghue, from Brown University, Providence, Rhode Island, and members of his group implanted a sensor comprised of an array of silicon microelectrodes onto the region of the motor cortex that controls arm and hand movement. The patient was a tetraplegic 25-year-old man whose cervical spinal cord had been transected 3 years earlier.

This "neuromotor prosthesis" included the implanted sensor, a decoder to translate firing neuron patterns into motor commands and a computer gateway (BrainGate; Cyberkinetics, Inc.).

The patient was instructed to imagine arm motions, during which the internal sensor detected brain cell activity that was converted into computerized signals, which permitted the patient's hand and arm to move.

Even 3 years after the injury, the researchers note, "motor cortex neurons can still be actively engaged and encode task-related information during the intention to move the limb ordinarily controlled by that motor cortex."

So far, the patient has been able to use the control signal to direct computer software, play video games, control a TV and to operate a robot arm and an electric prosthetic hand.

He predicted the development wireless telemetry so that the implant can be completely covered, peripheral nerve stimulation of paralyzed muscles, better movement algorithms, and improved feedback from the arrays.

Dr Shenoy added that stem cells may eventually be used for many of the same purposes addressed by the neuromotor prostheses.

The two research teams plan to focus on soldiers returning from the Iraq war with amputated limbs or paralysis. "If we fit them with a robotic arm or an esthetic prosthesis, they will need to control their movements, and stem cells will not be of much help there."

"What drives us is the patient, wanting to develop instruments to help them interact with the environment and provide independence," Dr Santhanam said. "Clinicians and patients should stay tuned because a lot of promising things are on the horizon to help patients."

Nature 2006;442:164-171,195-198.

Reuters Health Information 2006. © 2006 Reuters Ltd.