When an individual operates a prosthetic arm, especially a mind-controlled technology, it becomes extremely difficult to have complete motor control to do things like touch or grasp.
A team of bioengineers from the University of Pittsburgh Rehab Neural Engineering Labs has detailed in a new Science paper how brain stimulation that evokes tactile sensations can make it easier for a user to operate a brain-controlled robotic arm.
Grasping and Transferring Time Cut in Half
The team conducted an experiment that demonstrated that supplementing vision with artificial tactile perception cut the time it took to grasp and transfer objects in half. The median time of 20.9 seconds fell to 10.2 seconds.
Jennifer Collinger is co-senior author and Ph.D associate professor in the Pitt Department of Physical Medicine and Rehabilitation.
“In a sense, this is what we hoped would happen — but perhaps not to the degree that we observed,” said Collinger. “Sensory feedback from limbs and hands is hugely important for doing normal things in our daily lives, and when that feedback is lacking, people’s performance is impaired.”
The Study Participant
The study participant was Nathan Copeland, who became the first-ever individual to have tiny electrode arrays implanted in not just his brain’s motor cortex, but also his somatosensory cortex, which is an area of the brain that processes sensory information from the body.
The arrays enabled him to control the robotic arms with his mind and receive tactile sensory feedback, which is also similar to how neural circuits work.
“I was already extremely familiar with both the sensations generated by stimulation and performing the task without stimulation. Even though the sensation isn’t ‘natural’ — it feels like pressure and gentle tingle — that never bothered me,” said Copeland. “There wasn’t really any point where I felt like stimulation was something I had to get used to. Doing the task while receiving the stimulation just went together like PB&J.”
Copeland was involved in a car crash that resulted in him having limited use of his arms, so he enrolled in a clinical trial testing of the sensorimotor microelectrode brain-computer interface (BCI). He was implanted with four microelectrode arrays that were developed by Blackrock Microsystems.
The BCI operator went through a series of tests that required the pickuping up and transferring of several objects from a table to a raised platform. Tactile feedback was provided through electrical stimulation, which enabled the participant to complete tasks twice as fast compared to no stimulation.
Robert Gaunt is co-senior author and Ph.D. associate professor in the Pitt Department of Physical Medicine and Rehabilitation.
“We didn’t want to constrain the task by removing the visual component of perception,” said Gaunt. “When even limited and imperfect sensation is restored, the person’s performance improved in a pretty significant way. We still have a long way to go in terms of making the sensations more realistic and bringing this technology to people’s homes, but the closer we can get to recreating the normal inputs to the brain, the better off we will be.”