Paralyzed Patient Moves Prosthetic Arm With Thoughts Alone

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Main Category: Neurology / Neuroscience
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Article Date: 10 Oct 2011 - 10:00 PDT

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A paralyzed adult male patient used a brain computer interface to move a prosthetic arm - all he had to do was use his thoughts and the arm moved. Tim Hemmes touch hands with his girlfriend in an emotional high-five moment. Hemmes, 30, had a motorbike accident seven years ago which damaged his spinal cord, leaving him paralyzed.

The researchers say that Hemmes is the first patient in a new human study which is determining whether a paralyzed person's thoughts can be used to control an external device, such as a sophisticated prosthetic arm or a computer cursor.

A series of electrodes were placed on the surface of the patient's brain, so that he could control the external arm device. This project is being carried out by scientists at the University of Pittsburgh School of Medicine and UPMC Rehabilitation Institute.

The robotic arm and hand was designed by scientists at the Johns Hopkins University Applied Physics Laboratory.

With pure brain power, Hemmes managed to will the arm towards the palm of one of the researchers and then later to his girlfriend's hand.



Tim Hemmes does a high-five with his girlfriend (Photo: UPMC)


After successfully moving the arm and hand, Hemmes said:

"I put my heart and soul into everything they asked me to do," he said immediately after his achievement. "I got to reach out and touch somebody for the first time in seven years."

Head researcher, Michael Boninger, M.D., director of the UPMC Rehabilitation Institute, said:

'Seeing Tim reach out with a mechanical arm to touch his girlfriend was an unexpected and poignant bonus for all of us who are involved with this exciting project.

This first round of testing reinforces the great potential BCI technology holds for not only helping spinal cord-injured patients become more independent, but also enhancing their physical and emotional connections with their friends and family. It further motivates us to make this technology useful and available to those who need it. "

Co-investigator and UPMC neurosurgeon Elizabeth Tyler-Kabara, M.D., Ph.D., surgically placed a postage-stamp sized ECoG (electrocortigraphy) grid on the surface of Hemmes' brain during a two-hour procedure. Dr. Tyler-Kabara is assistant professor at the Dept. of Neurological Surgery, Pitt School of Medicine.

Tyler-Kabara explained:

"Before the procedure, we conducted several functional imaging tests to determine where his brain processed signals for moving his right arm. We removed a small piece of his skull and opened the thick layer of protective dura mater beneath it to place the grid over that area of motor cortex. We then put the dura and skull back with the wires on the outside of the skull but under the scalp."

Connecting wires were tunneled under the skin, down the patient's neck, and exited from his upper chest. From there they could be plugged into computer cables.

Over a period of four weeks, Hemmes and the research team tested the technology six days each week, both at the University premises and at the patient's home. Computer software, which had been developed by the researchers, can interpret neural signals picked up by the implanted brain grid.

With practice, Hemmes managed to move a ball around on the TV screen without any computer assistance, with what the scientists called "100% brain control". From moving a ball on the screen about, he worked on doing the same thing with a prosthetic robotic arm and hand. He tried to reach out to touch a target on a large-desk-mounted panel.

Getting the prosthetic arm to move was not the same as getting his real arm to move before he became paralyzed. Hemmes had to visualize flexing his thumb - to imagine it - this created a brain signal pattern the computer interpreted as "move left", or bending his elbow so that the object could be moved to the right.

Co-principal investigator Wei Wang, M.D., Ph.D., said:

"He mentally associated specific motor imageries with desired movement direction. It required concentration and patience, but this process seemed to get easier for him with practice, just like when someone learns to drive a car with a manual transmission. In future studies, we also will test other approaches, including the participant simply thinking up for up, down for down, and so on."

By the eighth session Hemmes had managed to make substantial progress. With special goggles on, which allowed him 3-D vision on the TV screen, he moved the ball up, down, left, right, and also backwards and forwards.

This progressed to moving the arm in several different directions - he eventually managed to reach out to his girlfriend and Dr. Wang with a spectacular high-five.





On the following day, September 22, Dr. Tyler-Kabara removed the ECoG brain grid and wiring from the patient during a short procedure.

The scientists are currently examining all the data they gathered during this trial. They are looking for five or more additional adults with brainstem strokes of spinal cord injuries who have either no use or extremely limited use of their hands and arms for further trials.

Volunteers sought for another study

They are also seeking volunteers for a another year-long human study involving a brain-computer interface that is a 10-by-10 array of miniscule electrode points that go into brain tissue at a depth of less than one-tenth of an inch and gather signals from 100 individual neurons.

One grid will be placed in the part of the brain that controls hand movement, will the other will be placed in another brain region which controls arm movements, Andrew Schwartz. Ph.D., co-principal investigator, explained.

Schwartz said:

"We anticipate that these penetrating grids can pick up very clear signals from the brain to reveal what motion is intended by the participant. The second grid will allow us to see what might be possible in controlling the fine movement of the fingers and hand, which is far more complicated but also could offer more useful function for the participant."

Successful animal experiment with avatar hand

A few days ago scientists from Duke University reported on two trained monkeys that used a brain-machine-brain interface to move an avatar hand to detect the texture of virtual objects. Their aim is to eventually create an external exoskeleton suit that paralyzed people could wear and walk around in; using just their brain to control movement and sense of touch. (Link to article)

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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