Every year, 15 million people worldwide suffer a stroke, and of these, five million are left permanently disabled. A new device designed by researchers at the Washington University School of Medicine demonstrates just how plastic and adaptable our brains really are. Consisting of a cap to detect electrical signals in the brain and a brace that is worn over a paralyzed hand, the device can help stroke victims retrain undamaged parts of their brain to regain control of paralyzed limbs.

The devices relies on a discovery made a decade ago. Despite a general understanding that the left side of the brain controls motor movement on the right side of the body, and vice versa, it was discovered that there is a small area of the brain that plays a role in planning movement on the same side of the body, milliseconds before the opposite hemisphere becomes active.

For example, this means that when someone has a stroke that damages the left side of their brain, they will likely experience some paralysis on the right side of their body. However, an electrical signal indicating an intention to move is still being generated on the undamaged right side of the brain. This signal now has nowhere to go, but by detecting these signals, the team realized it might be possible to retrain the undamaged part of the brain to regain control of those paralyzed limbs.

To this end, they developed a device called the Ipsihand, which detects these early movement-planning electrical signals in the brain and communicates with a brace that sits over the wearer's hand. When the Ipsihand detects these electrical signals. it moves the brace in a pincer-like grip.

"The idea is that if you can couple those motor signals that are associated with moving the same-sided limb with the actual movements of the hand, new connections will be made in your brain that allow the uninjured areas of your brain to take over control of the paralyzed hand," explains the study's co-senior author, Professor Eric Leuthardt.

The study recruited a group of stroke victims who were trained to use the device at home. All participants had suffered a stroke at least six months previously, as most stroke patients rapidly recover some abilities in the weeks immediately following a stroke, before plateauing after three months or so. The participants were directed to use the device for between 10 minutes and two hours per day, at least five days a week.

After 12 weeks of training their brains, the patients showed an average improvement of 6.2 points on the 57-point scale in a standard motor skills evaluation. The evaluation was designed to measure abilities such as grasping, gripping and pinching with their hands. While the ultimate results were quite minimal, they were reportedly enough to significantly improve the mobility satisfaction for each participant.

"For some people, this represents the difference between being unable to put on their pants by themselves and being able to do so," notes Professor Leuthardt.

Interestingly, the study found that the degree of patient improvement was not related to the volume of time each individual spent with the device, but was instead specifically related to how well the system could read the brain signals of an individual. The team points out that this means the system is sure to improve as our technological ability to read brain signals gets better.

The research highlights just how plastic and adaptable our brains really are. Despite dramatic brain injury damaging parts of the brain we can now potentially find ways to train those undamaged areas to take control over lost functions.

The study was published in the journal Stroke.

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