AI illustration adapted from material provided by Seitaro Iwama, Keio University lecturer.
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A research team at Keio University announced in April that it had succeeded in improving motor performance through imagery training alone, without subjects actually moving their bodies, by allowing them to visualize the state of their brains during the exercise.
The findings were published in the Proceedings of the National Academy of Sciences of the United States of America.
Because the method trains the brain directly, it could open the door to a new kind of training that requires no special equipment, dedicated space, or facility.
Training the Brain Directly
At the heart of the study is a technique known as neurofeedback, in which people monitor their own brain activity in real time and train themselves to control it. Brain activity, such as electrical signals or blood flow, is measured and analyzed in real time, then translated into visual cues or movements of an external device that are fed back to the subject.
Unlike conventional imagery training, which relies on simply imagining movement, neurofeedback lets subjects monitor and learn to regulate their own brain activity.
The Keio team has already been studying the use of neurofeedback in rehabilitation for stroke patients left with paralysis. Through a university-launched startup, it has commercialized medical equipment for that purpose, which has already been introduced at dozens of medical institutions across Japan.
In the latest study, the researchers examined whether neurofeedback could further enhance motor abilities that subjects already possess, not just restore lost motor function. The results showed that adults who trained themselves to control shifts in their brain state improved their motor performance.
Training Without Moving
In the experiment, electrodes placed on the subjects' scalps measured faint electrical signals in the brain. The researchers focused on brain waves known as sensorimotor rhythms, which are detected near the motor cortex. The amplitude of these brain waves increases when a person is at rest, but decreases when the person performs a movement.
A red bar indicating changes in this amplitude was displayed on a screen in front of each subject, allowing them to monitor their brain state. Artificial intelligence was also used to analyze the brain waves in real time and tailor the bar display to each individual.
While watching the red bar, the subjects repeatedly imagined two actions: moving their right wrist and relaxing it. They tried to control their thoughts so that the bar would extend toward a target marked by a green dashed line.
Although the subjects did not actually move their bodies, when they succeeded in reaching the target, a device attached to their right hand moved and sent electrical signals to the muscles. By providing feedback not only through the screen but also through physical sensory stimulation, the researchers aimed to enhance the training effect.
The experiment involved 41 men and women in their early 20s who underwent two days of rapid imagery training where they repeatedly imagined contracting and relaxing their muscles.
The subjects were divided into two groups. One received feedback based on their own brain state, while the other received feedback based on someone else's. Those who received genuine feedback showed shorter reaction times and improved ability to switch brain states. No such improvement was observed among those who received false feedback.
A Tool for Faster Movement
To determine whether the benefits of imagery training carried over to actual motor performance, the researchers also conducted an experiment in which subjects physically contracted and relaxed the muscles in their right hands. Those who had trained with genuine feedback also showed shorter reaction times in the actual movement task.
The ability to instantly tense or relax muscles at the right moment is closely tied to what athletes call the sharpness of movement and explosive power. The findings are expected to help improve athletes' performance in track and field, swimming, and other sports that require split-second reactions.
"We want to bring this technology for improving motor performance through neurofeedback to real athletes," said Seitaro Iwama, a lecturer in neuroscience at Keio University and the lead author of the paper.
The method may also have applications in areas such as E-sports, where quick reactions are essential, as well as musical performance.
The device used in the experiment was an EEG monitor worn like a cap. It does not require invasive procedures such as cutting into the brain or implanting electrodes. Although the study used a high-density EEG system with 128 electrodes placed on the scalp, the researchers say training of this kind only requires measurement of activity in the motor cortex, meaning the number of electrodes could be reduced.
Iwama and his colleagues are now developing a headphone-style EEG device that uses just three electrodes and can be worn more easily. The device would transmit measured brain waves to a computer or smartphone via Bluetooth. They hope it will eventually allow athletes and others to train conveniently at home, without visiting a laboratory.
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Author: Maki Matsuda, The Sankei Shimbun
(Read this article in Japanese)
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