In the latest advance in cyborg technology, scientists have replaced the dysfunctional part of a rat’s brain with electrodes and a computer chip. It’s the part of the brain that coordinates movement, so when the chip is off the rat can’t perform a simple movement task. But power up the chip and it performs perfectly. The newest member of the Rat Borg Collective could lead to treatments for people who have impaired movement due to brain damage caused by trauma or stroke.
Scientists at Tel Aviv University first damaged the rat’s cerebellum, the part of the brain involved in the coordination and timing of movements. The researchers then tried to train the impaired rat to blink in response to a tone. Rats with damaged cerebellums were unable to learn the task. When they plugged in the brain implant, however, the rats learned the task just fine.
The tone that failed to make the brain-damaged rats blink was picked up by electrodes and processed in a chip sitting on the rat’s scalp. By bypassing the damaged brain area, the chip not only processed the incoming signals but sent out signals to areas in the brainstem that sent signals to the eye to blink. By replacing brain circuitry with microchip circuitry the researchers were able to return normal behavior to the rats.
Other chip implants have proven successful in mimicking brain function. Cochlear implants help the deaf to hear by transforming sounds into electrical impulses, which then stimulate neurons that pass the signal on to the brain. Robotic prosthetic limbs can now detect neuronal signals in the limbs to control movement. But these implants only process information in one direction. The cerebellar implant, however, represents a major advance in electronic prosthetics as it not only processes incoming sensory information (tone), but it uses that information to generate an output (blink).
“It’s proof of concept that we can record information from the brain, analyze it in a way similar to the biological network, and return it to the brain,” the study’s lead author, Matti Mintz, told New Scientist. He presented the work last month at the Strategies for Engineered Negligible Senescence (SENS) Conference in the UK. As its name somewhat implies, the SENS Foundation supports research that slows or reverses the aging process. Computer chips could not only restore function to an aging part of the brain, but they might one day improve normal functions such as memory.
As far as brain systems go, the processing involved in the cerebellum and Mintz’s implant are relatively simple. The cerebellum is largely made up of repeating microcircuits that make it one of the better understood areas of the brain. “We know its anatomy and some of its behaviors almost perfectly,” said Mintz.
Extending their “proven concept” to other brain areas or even just cerebellar tasks that are more complicated will no doubt prove challenging. Mintz and his colleagues say they plan to expand their chip’s processing to include areas of the cerebellum involved in other movements. An important detail in the current study is that the rat was anesthetized. With the circuity intact, it wasn’t necessary for the rat to be awake to connect tone with eye blink. For more complex movements, however, they’re going to have to wake the rat up. That poses a major technical challenge as the precise sensory signals that the chip needs to process to generate a proper output are easily disrupted by a moving rat. It’s a catch-22 in which they want to study movement but they don’t want the rat to move. Overcoming this obstacle may require the development of new technologies, but Dr. Francesco Sepulva of the University of Essex – who was not involved in the study – has faith. “It will likely take us several decades to get there,” he told the New Scientist, “but my bet is that specific, well-organized brain parts such as the hippocampus or the visual cortex will have synthetic correlates before the end of the century.”