Did you know it's possible to control a robotic arm or a wheelchair with just your thoughts, through a device called a brain-computer interface (BCI)? But for many users, learning to operate these systems is slow, difficult and, in some cases, unattainable.
Researchers at The University of Texas at Austin discovered a novel way to accelerate this learning process: a gentle electrical nudge to the spine before BCI training.
In a new study published in the Proceedings of the National Academy of Sciences , researchers from the Cockrell School of Engineering and Dell Medical School found that noninvasive spinal stimulation can help the user focus on the task at hand, significantly speeding up the learning curve for brain-computer interfaces. This stimulation was shown to cut learning time in half.
"By using spinal stimulation to prime the brain, we're not just speeding up learning—we're also making it possible for people who previously struggled to use BCIs to gain control," said José del R. Millán, professor in the Cockrell School's Chandra Family Department of Electrical and Computer Engineering and the Department of Neurology at Dell Med. "This opens up exciting possibilities for motor rehabilitation and assistive technology."
Brain-computer interfaces detect brain signals associated with movement intentions and translate them into commands for external devices. These systems rely on specific brain activity patterns called sensorimotor rhythms, which are generated when a person imagines moving a limb to control a device.
The researchers used a technique called transcutaneous electrical spinal stimulation, which involves delivering mild electrical pulses to the spinal cord through electrodes placed on the skin. The stimulation temporarily inhibits certain areas of the brain, allowing the neural activity associated with motor imagery to become more focused and stable. This "preconditioning" effect helps users produce stronger and more consistent brain signals, making it easier for the BCI system to interpret their intentions.
"Think of it like tuning a radio to the right frequency," said Hussein Alawieh, a former graduate student in Millán's lab who was the first author of the study. "Spinal stimulation helps the brain filter out noise and focus on the signals that matter most for controlling the BCI. This makes the learning process faster and more effective."
The researchers conducted experiments involving 20 healthy participants and two individuals with spinal cord injuries. Participants were divided into two groups: one received spinal stimulation before each training session, while the other rested for the same amount of time. Here's what happened:
- Faster learning: Participants who received spinal stimulation showed significant improvements in BCI performance after just two training sessions, compared to five sessions for the control group.
- Improved accuracy: By the end of the training, the stimulation group achieved higher accuracy in controlling the BCI, with stronger and more focused brain activity patterns.
- Long-lasting effects: The benefits of the spinal stimulation persisted for at least a week after training, suggesting that the technique helps users retain their skills over time.
The researchers also tested their technique on individuals who had previously failed to learn BCI control using traditional methods. After undergoing the stimulation protocol, all participants in this "slow learner" group successfully gained control of the system, a sign that this technique could open up BCI to more potential users.
BCIs are already used to help individuals with paralysis regain some level of independence. In addition, this technique could be used as part of rehabilitation programs for stroke survivors and others with motor impairments.
BCIs have been shown to promote brain plasticity—the ability of the brain to reorganize itself and form new connections, which is critical for recovery. Faster and more reliable BCI control could enhance these therapeutic effects, potentially leading to better outcomes.
While this study focused on hand movements, the researchers believe their approach could be extended to more complex tasks, such as controlling robotic limbs with multiple degrees of freedom. They also plan to explore using their spinal stimulation technique in other populations, including individuals with severe neurological conditions.
"Our ultimate goal is to improve quality of life for people with motor impairments," said Millán. "Whether it's helping someone regain the ability to move their arm or enabling them to operate a wheelchair with their thoughts, this technology has the potential to make a real difference."
The full team includes Satyam Kumar and Deland Liu of the Chandra Family Department of Electrical and Computer Engineering, professor Ann Majewicz Fey and Jonathan Madera of the Walker Department of Mechanical Engineering and Frigyes Samuel Racz of the Dell Medical School. The Coleman Fung Foundation funded the research.
