Victims of traumatic brain injuries often lose the ability to perform certain actions, due to the fact that two or more regions of their brain are no longer able to communicate with one another. However, in the same way that a spliced-in wire can circumvent a broken electrical connection, scientists have recently demonstrated that an electronic brain-machine-brain interface can restore lost abilities to brain-damaged rats. The research could lead to the development of prosthetic devices for treatment of injured humans.

The study was carried out by a team from Case Western Reserve University and the University of Kansas Medical Center, and utilized rats that had learned to reach through a narrow opening in order to grasp food pellets. That behavior required communication between neurons in the posterior and anterior parts of the brain, which were surgically separated after the behavior had been learned. As a result, the rats were no longer able to retrieve pellets.

In order to undo the damage, a "closed-loop microelectronic system" was installed on top of their heads. This prosthetic system consisted of a custom-designed microchip embedded in a small circuit board, that was connected to two sets of microelectrodes. One of those sets was implanted in the posterior brain, and one in the anterior.

When neurons in the anterior produced electrical signals, an algorithm running in the chip detected them and separated them from other distracting background "noise." The electrodes implanted in the posterior subsequently delivered the signal to the neurons in that region, in the form of electrical pulses.

Two weeks after having received the fully-functioning interface, brain-damaged rats were once again able to retrieve pellets with the same success rate as unimpaired rats – close to 70 percent. By contrast, rats receiving random stimuli had a success rate of less than 50 percent, while rats receiving no stimulus at all were closer to 25 percent.

Although the research is still ongoing, it is hoped that once the two parts of the brain have communicated for a long enough period of time, they will have formed new connections and the interface will no longer be needed.

The device was built by Case Western's Prof. Pedram Mohseni, and tested in the University of Kansas lab of Prof. Randolph J. Nudo. A paper on their research was recently published in the journal Proceedings of the National Academy of Sciences.

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