There has been a lot of progress over the past few years in the field of brain-computer interfaces, a technology that may give severely paralyzed people the ability to use robotic arms and legs. As anyone with two arms knows, one is not enough for many tasks. So researchers at Johns Hopkins University have successfully implanted two microelectrode arrays, one on each side of a disabled man’s brain, that have been used to control two independent robotic arms and to also deliver tactile sensations. This is the first time that anyone has been able to accomplish such a feat, and it bodes well for the future of the field.
The team used the Modular Prosthetic Limb (MPL), a device developed for DARPA, to interface with the disabled volunteer. The MPL is, arguably, the most advanced prosthetic yet developed, as it has a bunch of pressure, force, and acceleration sensors, and the ability to have its fingers be controlled independently.
“We are trying to enable a person with quadriplegia to use a direct neural interface to simultaneously control two assistive devices and, at the same time, feel touch sensation when the devices make contact with objects in the environment,” explained Dr. Brock Wester, a principal investigator of the research, in a Hopkins press release.
One challenge in achieving a good interface between the brain and an electrode array, and therefore unlocking the ability to move the robotic arms, is accurately positioning the implants in the right locations. The Hopkins team developed a novel method, which is used during surgery and that creates real-time maps of brain activity, to locate the optimal implant sites.
Following implantation, the researchers worked with the volunteer to study what he feels in response to different brain stimulation regimes. Tuning this accurately may lead to users being able to more naturally sense things being touched and manipulated when using the powered prostheses.
“For the first time, our team has been able to show a person’s ability to ‘feel’ brain stimulation delivered to both sides of the brain at the same time. We showed how stimulation of left and right finger areas in the brain could be successfully controlled by physical touch to the MPL fingers,” explained Dr. Matthew Fifer, the technical lead on the project.
Here’s a video of the volunteer subject moving a pair of robotic arms with his mind:
Here he is describing what it is like to be doing this: