Paralyzed Patients Use Thoughts to Control Robot Arm

Fran Lowry

June 05, 2012

June 6, 2012 — A woman paralyzed because of a brainstem stroke she sustained in 1996 was able to reach for and sip a drink on her own, without help from a caregiver, by using her thoughts to control a robotic arm.

Another man, similarly paralyzed since 2006, was able to cause the robotic arm to perform reach and grasp tasks by using his thoughts to direct the device.

These landmark achievements using a neural interface system in patients with tetraplegia are from the National Institutes of Health (NIH)–funded BrainGate2 trial, published online May 17 in Nature.

"Years after the onset of paralysis, we found that it was still possible to record brain signals that carry multi-dimensional information about movement, and that those signals could be used to move an external force," lead investigator Leigh Hochberg, MD, PhD, associate professor of engineering at Brown University in Providence, Rhode Island, and a critical care neurologist at Massachusetts General Hospital (MGH), Harvard Medical School, in Boston, said in a statement.

Pattern of Impulses

The robotic arm is part of an investigational device called the BrainGate neural interface system, a type of brain-computer interface that aims to put robotics and other assistive technology under the control of the brain.

It consists of a sensor to monitor brain signals and computer software and hardware that turns these signals into digital commands for external devices. The sensor is a small patch of silicon containing 100 hair-thin electrodes that can record the activity of small groups of brain cells and is implanted into the motor cortex, the part of the brain that directs movement.

A neural interface system allows a woman with tetraplegia to drink.

"Basically the computer takes this pattern of neuron impulses, and then guesses at what this pattern means, and then tells the robot arm to move a little bit to the left, to the right, or up and down or back and forth, and by doing that repeatedly, the robot arm now is responding to the changing pattern in the brain and moving around," senior author John P. Donoghue, PhD, professor and neuroscientist at Brown University and Director of the Brown Institute for Brain Science, told Medscape Medical News. "The amazing thing is, it works!"

Dr. Donoghue, who is also a research scientist at the Providence Veterans Affairs Hospital, has been developing this technology for the past several years and admits he is very excited about the potential of the device.

"People don't actually have a whole lot of insight into what's really going on, they just know that when they think about reaching out into space, what is happening is all the areas of the brain that are normally involved in that movement are converging on this motor cortex and generating a pattern and then it just happens," he said.

Dr. John P. Donoghue

Currently, patients have to be connected by a cable to the sensor. The next step is to get rid of that and make a wireless implant that has the processors inside the body. "We are working on that now," Dr. Donoghue said.

Early Promise

Daofen Chen, PhD, director of the Sensory Motor Integration Program at the National Institute of Neurologic Disorders and Stroke, stressed that the promise of this technique, although considerable, may not be realized for 20 years or longer.

"Before this can be used in the clinic, it would need a significant amount of basic translational studies," Dr. Chen told Medscape Medical News.

He emphasized that such work is very labor intensive and necessitates a multidisciplinary approach.

"All of this accomplishment has been due to years of basic research in primates. The very reason why we are confident enough to move on to test it in humans is because of the work we have done in monkeys, and these types of experiments in primates are very difficult to do," Dr. Chen said.

"We also have to give credit to informational technology, for the development of micro size electrodes, the computational power needed to decode these dozens of channels, for enabling this project," he said.

The research has also been supported by an "unprecedented" collaboration among several federal agencies, Dr. Chen said.

The NIH, the Defense Advanced Research Projects Agency, the Department of Veterans Affairs, and the US Food and Drug Administration have all worked together on this project, he noted, "and it is very unusual to have several federal agencies working this closely."

Dr. Hochberg and Dr. Chen have disclosed no relevant financial relationships. Dr. Donoghue is a former chief scientific officer and director of CKI.

Nature. 2012;485:372-375. Published online May 17, 2012. Abstract


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