Technology To Help Patients Control Assistive Devices With Their Thoughts

Our ultimate aim is to develop technologies that can give patients with physical disabilities control of assistive devices that will help restore their independence.
—Dr. Boninger

Early in 2011, researchers at the University of Pittsburgh were awarded funding for two projects that will place brain-computer interfaces (BCI) in patients with spinal cord injuries to test if it is possible for them to control external devices, such as a computer cursor or a prosthetic limb, with their thoughts. View the full announcement

The two projects build upon ongoing research conducted in epilepsy patients who had the interfaces temporarily placed on their brains and were able to move cursors and play computer games, as well as in monkeys that through interfaces guided a robotic arm to feed themselves marshmallows and turn a doorknob.

Study Leaders

Michael L. Boninger, MD, director, UPMC Rehabilitation Institute, chair, Department of Physical Medicine and Rehabilitation, Pitt School of Medicine, is a senior scientist on both projects. Below, Dr. Boninger discusses the projects.

Elizabeth Tyler-Kabara, MD, PhD, UPMC neurosurgeon and assistant professor of neurological surgery and bioengineering, University of Pittsburgh Schools of Medicine and Engineering, is the lead surgeon on both projects. Below, Dr. Tyler-Kabara describes the project, the first patient, and the surgery.

Andrew Schwartz, PhD, professor of neurobiology, University of Pittsburgh School of Medicine, is a senior investigator on both projects. Below, Dr. Schwartz discusses how his previous work with monkeys has informed the current projects.

Project One
Funded by the National Institutes of Health, this project places a BCI based on electrocorticography (ECoG) on the motor cortex surface of a spinal cord injury patient’s brain for up to 29 days. The neural activity picked up by the BCI will be translated through a computer processor, allowing the patient to learn to control computer cursors, virtual hands, computer games and assistive devices such as a prosthetic hand or a wheelchair.

Project Two
This project is funded by the Defense Advanced Research Projects Agency (DARPA), and is part of a program led by the Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Md. It will further develop technology tested in monkeys by Dr. Schwartz and uses an interface that is a tiny, 10-by-10 array of electrodes that is implanted on the surface of the brain to read activity from individual neurons. Those signals will be processed and relayed to maneuver a sophisticated prosthetic arm.

Early Results
Seven years since a motorcycle accident damaged his spinal cord and left him paralyzed, 30-year-old Tim Hemmes, the first BCI trial participant reached up to touch hands with his girlfriend in a painstaking and tender high-five. It was a unique, mechanically jointed arm and hand, designed by the Johns Hopkins University Applied Physics Laboratory, that Mr. Hemmes willed to extend first toward the palm of a researcher on the team and, a few minutes later, to his girlfriend’s hand. View full press release of early results.

On Aug. 25, a domino-sized electrocortigraphy (EcoG) grid adapted from seizure-mapping brain electrode arrays was placed on the surface of Mr. Hemmes’ brain during a two-hour operation performed by Elizabeth Tyler-Kabara, MD, PhD. Before the procedure, several functional imaging tests were conducted to determine where his brain processed signals for moving his right arm. During the surgery, a piece of his skull was lifted and the thick layer of protective dura mater beneath it to place the grid over that area of motor cortex. Then the dura and skull was put back with the wires on the outside of the skull but under the scalp.”

Dr. Tyler-Kabara tunneled the connecting wires under the neck skin to exit from the upper chest, where they could be periodically hooked up to computer cables. For six days per week for the next four weeks, Mr. Hemmes and the team tested the technology. The researchers had developed computer software programs in earlier studies to interpret the neural signals sensed by the brain grid.

It wasn’t the simultaneous thought-and-move process that he knew from before becoming paralyzed. Instead, he imagined flexing his thumb, which created a brain signal pattern that the computer was set to interpret as “move left,” or bending his elbow to move the object right, explained co-principal investigator Wei Wang, MD, PhD, assistant professor, Department of Physical Medicine and Rehabilitation, University of Pittsburgh School of Medicine.

After about four sessions, Mr. Hemmes tackled more complicated tasks. While wearing special goggles to properly view a three-dimensional TV screen, he moved the ball in the previous directions, and also to the front or back. He also practiced moving the arm in all directions, culminating in the joyful moments after formal testing had been completed when he reached out to his girlfriend and to Dr. Wang. Dr. Tyler-Kabara removed the ECoG brain grid and wiring in a short operation the next day.

The researchers are now analyzing the data, and are seeking for further testing at least five more adults with spinal cord injuries or brainstem strokes who have very little or no use of their hands and arms.