Researchers recently used a neural prosthesis in a rat model of brain injury to restore the animals’ ability to reach and grasp food through a narrow opening. The prosthesis, known as a brain-machine-brain interface, is comprised of a closed-loop microelectronic system.
According to a news release from Case Western Reserve University, the device is designed to record signals from one part of the brain, process them in real time, and bridge the injury by stimulating a second part of the brain that had lost connectivity.
Pedram Mohseni, PhD, professor of electrical engineering and computer science at Case Western Reserve, who built the brain prosthesis, explains that researchers from Case Western Reserve and the University of Kansas Medical Center aimed to determine, “If you use this device to couple activity from one part of the brain to another, is it possible to induce recovery from TBI?”
Mosheni adds that the researchers found that it was indeed possible to use a closed-loop neural prosthesis to facilitate repair of a brain injury. The researchers determined this, the release notes, by testing the prosthesis in a rat model of brain injury in the laboratory of Randolph J. Nudo, PhD, professor of molecular and integrative physiology at the University of Kansas.
Nudo reportedly mapped the rat’s brain and developed the model in which anterior and posterior parts of the brain that control the rat’s forelimbs are disconnected. The device was positioned on top of each animal’s head. The release states that 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.
Researchers explain that the device amplifies signals called neural action potentials, which are produced by the neurons in the anterior of the brain. An algorithm then separates the recorded brain spike activity from noise or other artifacts. As each spike is detected, the microchip transmits a pulse of electric current to stimulate neurons in the posterior part of the brain, artificially connecting the two brain regions.
The results suggest that 2 weeks following the implantation of the prosthesis, which was run continuously, rat models using the full closed-loop system had recovered nearly all function lost due to injury. As a result, the animals were able to retrieve a food pellet close to 70% of the time, or as well as normal, uninjured rats, researchers say.
Additionally, the results indicate that rat models who were given random stimuli from the device retrieved less than half the pellets, and those that received no stimuli retrieved about a quarter of them. Mosheni notes that researchers still must determine whether the implant must be left in place for the term of the lifespan or if it can be removed after 2 or 6 months, if and when new connections have been formed in the brain.
Mosheni and Nudo also emphasize the need for more systematic studies to determine what happens in the brain that leads to restoration of function.
[Source: Case Western University]