Researchers with the Cortical Bionics Research Group discovered a method for encoding natural touch sensations of the hand via specific microstimulation patterns in implantable electrodes in the brain. The discovery allowed the participants with spinal cord injuries to control a bionic arm with their brains and to feel tactile edges, shapes, curvatures, and movements, that until now have not been possible.
The Cortical Bionics Research Group includes the University of Pittsburgh, University of Chicago, and Northwestern University. Its mission is to build next-generation intracortical brain-computer interfaces (BCIs) that enable dexterous control of bionic hands by people with paralysis or amputation.
For individuals with a spinal cord injury, the electrical signals coming from the hand to the brain that should allow them to feel tactile sensations are being blocked by the injury. The research aimed to improve the usability of an extracorporeal bionic limb mounted on a wheelchair or similar equipment close to the user.
For the study, two participants were fitted with chronic brain implants in the sensory and motor regions of the brain that represent the arm and hand. Over the course of several years, the researchers were able to record and decode the patterns of electrical activity that occurred in the brain related to motor intention of the arm and hand.
After the decoding, the researchers typed specific stimulations directly into the users’ brains via the implants, and the participants were able to accomplish a series of complex experiments that required rich tactile sensations.
“We found a way to type these ‘tactile messages’ via microstimulation using the tiny electrodes in the brain, and we found a unique way to encode complex sensations. This allowed for more vivid sensory feedback and experience while using a bionic hand,” said Giacomo Valle, PhD, lead author of the study and assistant professor at Chalmers University of Technology.
Editor’s note: This story was adapted from materials provided by Chalmers University of Technology.
The study, “Tactile edges and motion via patterned microstimulation of the human somatosensory cortex,” was published in Science.
