Summary: Using a novel brain-computer interface, researchers restored a functional sense of touch to a 28-year-old man with a severe spinal cord injury, significantly improving his hand control and object interaction.
Source: Cell Press
Researchers aiming to restore limb function for people with paralysis emphasize that touch is more than a convenience—it is essential for smooth, natural movement. In a study published April 23 in the journal Cell, teams from Battelle and The Ohio State University Wexner Medical Center report restoring perceptible touch to the hand of a research participant with a clinically severe spinal cord injury using an innovative brain-computer interface (BCI). The system detects tiny, otherwise imperceptible neural signals and converts them into artificial sensory feedback the participant can feel, producing substantial gains in motor performance.
“We’re taking subperceptual touch events and boosting them into conscious perception,” says Patrick Ganzer, principal research scientist at Battelle and first author on the study. “When we achieved that, several functional improvements followed. It was a big eureka moment when the participant first reported feeling his hand.”
The participant, Ian Burkhart, was injured in a diving accident in 2010. Since 2014 he has collaborated with researchers on a project called NeuroLife that aims to restore use of his right arm. The NeuroLife device pairs skin electrodes and sensors with a small implant in the motor cortex. Signals from the brain are decoded and routed—via wires that bypass the damaged spinal cord—to stimulate the muscles of the arm and hand. With this setup Burkhart can perform everyday tasks such as lifting a coffee mug, swiping a credit card, and even playing Guitar Hero.
Before this advance, Burkhart often experienced his hand as disconnected from himself. “He sometimes felt like his hand was foreign because of the lack of sensory feedback,” Ganzer explains. Controlling the hand required intense visual attention, making multitasking—such as drinking a soda while watching television—difficult or impossible.
The investigators discovered that although Burkhart reported almost no sensation in his hand, skin stimulation still generated a neural signal in his brain. That signal was so small it remained below conscious awareness. Ganzer notes that even in cases considered “clinically complete” spinal cord injuries, tiny bundles of nerve fibers often remain intact. The team’s challenge was to amplify those residual signals so the brain would register them as touch.
They accomplished this by converting the subperceptual signals into haptic feedback. Haptic feedback—like a phone vibration or a game controller buzz—delivers tactile cues the user can feel. In this system, touch-related activity from Burkhart’s skin was detected, decoded, and translated into artificial haptic sensations that travel back to his nervous system in a form he can perceive.
The enhanced BCI produced three major functional gains. First, it enabled Burkhart to detect objects by touch alone with reliable accuracy—an important step toward autonomous object retrieval without constant visual monitoring. Second, it is the first BCI demonstrated to restore both touch and movement simultaneously; experiencing touch while moving provided Burkhart with a stronger sense of agency, faster performance, and easier coordination. Third, the system decodes pressure-related signals so he can modulate grip force—using a light touch for fragile items like a Styrofoam cup and firmer force for heavier objects—reducing drops and breakage.
Longer-term, the team aims to translate the laboratory system into a practical, user-friendly device for daily life. They are developing a next-generation sleeve with embedded electrodes and sensors that could be put on and removed easily, and they plan to replace bulky computer control with tablet-based interfaces to make the system smaller and more portable.
“It has been amazing to see sensory information emerge from a device that was originally designed only to let me control my hand in one direction,” Burkhart says. The combined sensory and motor restoration has made his interactions feel more natural and useful.
Funding: This study was supported by Battelle Memorial Institute and The Ohio State University Center for Neuromodulation.
About this neuroscience research article
Source:
Cell Press
Media Contacts:
Carly Britton – Cell Press
Image Source:
The image used in this article is in the public domain.
Original Research: Closed access
“Restoring the Sense of Touch Using a Sensorimotor Demultiplexing Neural Interface” by Patrick Ganzer et al., published in Cell. DOI: 10.1016/j.cell.2020.03.054
Abstract
Restoring the Sense of Touch Using a Sensorimotor Demultiplexing Neural Interface
Highlights
• After spinal cord injury, subperceptual touch signals still reach the human motor cortex.
• A brain-computer interface can leverage those signals to restore the sense of touch.
• Demultiplexing sensorimotor signals further enhances functional recovery.
• Touch-regulated grip force enables automated movement sequences and grip reanimation.
Summary
Paralyzed muscles can be reanimated after spinal cord injury using a BCI that enhances motor output. However, the sense of touch is a critical component of effective motor control. This study shows that a person with a clinically complete spinal cord injury can use a BCI to reanimate both movement and conscious touch by harnessing residual sensory signals from the hand. In the primary motor cortex (M1), subperceptual touch signals are demultiplexed from motor intention, enabling intracortically controlled, closed-loop sensory feedback. The closed-loop demultiplexing BCI substantially restored object touch detection and improved multiple sensorimotor functions. The system also decodes afferent grip intensity from M1 to regulate grip force, demonstrating that subperceptual neural activity can be decoded and transformed into conscious perception to meaningfully augment function.
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