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Injuries to the spinal cord disrupt the essential communication between the brain and the spinal circuits situated below the site of injury, often leading to paralysis. Researchers are exploring methods to re-establish this communication, with the aim of facilitating rehabilitation and potentially restoring movement.
Ismael Seáñez, an assistant professor in biomedical engineering at the McKelvey School of Engineering at Washington University in St. Louis and a neurosurgery faculty member at WashU Medicine, alongside his research team including doctoral student Carolyn Atkinson, has developed a novel decoder designed to restore this critical communication pathway. Their experiments involved 17 participants without spinal cord injuries, during which they utilized transcutaneous spinal cord stimulation—applying noninvasive electrical pulses externally to cue movement in the lower leg.
The findings of this study were published online on April 25, 2025, in the Journal of Neuro Engineering and Rehabilitation.
The research team employed a specialized cap embedded with noninvasive electrodes to monitor brain activity through electroencephalography (EEG). Participants donned the cap and were instructed to extend their leg at the knee, and then simply to think about extending their leg while keeping it still. This enabled researchers to capture and analyze the brain wave activity associated with both scenarios.
The collected neural activity was then input into the decoder, allowing it to learn how brain waves correspond to actual movement versus the intention to move. The researchers discovered that both the physical act of movement and the mental visualization of it employed similar neural patterns.
“After we train the decoder with this data, it becomes adept at predicting movement intentions based on neural activity, even in the absence of visible movement,” Seáñez noted. “We demonstrate the capability to identify when a person is contemplating moving their leg, regardless of whether the leg moves or not.”
To ensure the accuracy of their data, the research team implemented controls that confirmed participants were genuinely imagining movement rather than physically moving.
“Physical movements can introduce noise into the signal, complicating our predictions,” Seáñez explained. “Our goal is to decode movements based on the intention or brain activity, which is why we instruct participants to imagine extending their leg while utilizing the same algorithm trained on actual movements to determine whether they are imagining movement.”
Seáñez emphasized that the study presents two crucial insights.
“First, it’s indicative that we are successfully decoding movement intentions rather than mere artifacts or noise. Second, for individuals with spinal cord injuries who cannot physically move their legs, we can leverage their imagined movements to train our decoder.”
This proof-of-concept study marks a significant step toward creating a noninvasive brain-spine interface. Such a system could utilize real-time predictions to provide transcutaneous spinal cord stimulation, aimed at enhancing voluntary movement in isolated joints during rehabilitation for spinal cord injury patients.
Looking ahead, the team intends to explore the viability of a generalized decoder, trained using data from all participants, to assess if a universal model can perform comparably to individualized decoders. This approach may simplify the implementation of such technology in clinical environments.
Funding for this research was secured from various sources, including the McDonnell Center for Systems Neuroscience at Washington University; the National Institutes of Health (grants K12-HD073945, K01-NS127936, R01-EB026439, P41-EB018783); as well as the Department of Biomedical Engineering and the Department of Neurosurgery at WashU Medicine.
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