New Neural Prosthesis Restores Behavior After Brain Injury

Brain injury can cause a host of impacts after the initial accident. Behavior can be influenced and affect an individual for years to come. Now, though, researchers have designed a neural prosthesis that restores behavior in brain injured rats. The findings could lead to the creation of a similar device for humans in the future.

About 1.5 million Americans, including soldiers in Afghanistan and Iraq, suffer traumatic brain injuries (TBI). An additional 800,000 individuals suffer from strokes that result in weakness or paralysis in the United States, annually. Developing ways to help those suffering from these injuries can improve their quality of life in the future.

The prosthesis, called a brain-machine-microelectronic system is a closed-loop microelectronic system. It records signals from one part of the brain, processes them in real time and then bridges the injury by stimulating a second part of the brain that had lost connectivity. The scientists tested this device in rats. More specifically, the researchers mapped the rat's brain and developed a model in which anterior and posterior parts of the brain that control the rat's forelimbs are disconnected.

Atop each rat's head, the brain-machine-brain interface is a microchip on a circuit board smaller than a quarter connected to microelectrodes implanted in the two brain regions. This device amplifies signals and an algorithm separates these signals, recorded as brain spike activity, from noise and other artifacts. With each spike, the microchip sends a pulse of electric current to stimulate neurons in the posterior of the brain, which artificially connects the two brain regions. After just two weeks of the prosthesis being implanted, the rats had recovered nearly all of the functions they had lost due to injury.

"If you use the device to couple activity from one part of the brain to another, is it possible to induce recovery from TBI? That's the core of this investigation," said Pedram Mohseni, one of the researchers, in a news release. "We found that, yes, it is possible to use a closed-loop neural prosthesis to facilitate repair of a brain injury."

Currently, the researchers hope to make a device that humans can use. In addition, they want to see if the implant must be left in place for life or if it can be removed after a few months once the connections have been formed in the brain.

The findings are published in the journal Proceedings of the National Academy of Sciences.