Researchers from the University of California, Irvine, along with collaborators at Caltech and the Keck School of Medicine at USC, announced on Apr. 16 that they have developed a brain-computer interface system enabling a person to control a robotic exoskeleton for walking using only brain signals. The system also provides artificial sensation in the legs through direct electrical stimulation of the sensory cortex.
The development is described as an important step toward restoring ambulatory function for people living with spinal cord injuries and paralysis. The findings were published in the journal Brain Stimulation.
“Millions of people worldwide suffer from paralysis from spinal cord injury, with loss of lower-extremity motor and sensory function leading to wheelchair dependence and increased risk of serious secondary conditions including heart disease, osteoporosis and pressure ulcers,” said Dr. An Do, UC Irvine associate professor of neurology. “Recovering the ability to walk ranks among the highest rehabilitation priorities for paralyzed individuals.”
According to Do, while robotic gait exoskeletons have shown promise in helping restore walking ability, current systems are limited by manual controls and lack sensory feedback—factors that can slow gait speed and increase fall risk. The new bidirectional brain-computer interface (BDBCI) addresses these challenges by decoding motor intent from electrocorticography signals recorded directly from leg motor areas in the brain while delivering targeted electrical stimulation to create artificial sensations corresponding to leg movement.
“This work demonstrates that it’s feasible to restore both the motor and sensory dimensions of walking using a single, compact, embedded brain-computer interface system,” Do said. “We believe this lays a critical foundation for the development of fully implantable systems that could one day give paraplegic patients a meaningful and natural sense of movement.”
The study participant was a 50-year-old woman who operated the BDBCI-controlled exoskeleton across multiple exercises during epilepsy evaluation involving subdural electrocorticography implantation. She achieved high performance quickly according to researchers’ observations during ten exercises without any adverse events reported.
Dr. Charles Liu, professor at USC’s Keck School of Medicine Neurorestoration Center, said: “Although interhemispheric ECoG implantation is more complex than other conventional approaches, our team demonstrated that it can be performed safely and yields superior results.” He added that accessing leg motor cortex via this method provides more robust neural signal modulation associated with leg movements.
Lead author Jeffrey Lim highlighted portability as key: “This type of portability is necessary to be practical for patients’ everyday use. We hope that our system can serve as a prototypical example for such technologies henceforth.”
Looking ahead, co-author Payam Heydari outlined plans for further miniaturization toward fully implantable devices: “Such a system would eliminate transdermal components that pose infection risks and enable chronic implantation in paraplegic spinal cord injury patients.”
Caltech’s Richard Andersen commented on broader implications: “This study by UC Irvine’s Jeffrey Lim and colleagues represents an important proof of concept for a bidirectional interface for walking… This research provides a new avenue for more naturalistic and effective use of walking exoskeletons.”
The research team included contributors from several institutions including Rancho Los Amigos National Rehabilitation Center in Downey; their work received approval from institutional review boards at UC Irvine and Rancho Los Amigos National Rehabilitation Center.
