Study in Brain Flexibility Could Mean Advances for Neuroprosthetics

Neuroscientists at the University of California, Berkeley and the Champalimaud Center for the Unknown in Portugal have demonstrated that through brain plasticity, the same brain circuits used to learn motor skills can be used to master purely mental tasks as well, according to a press release.

The study was conducted to investigate how the brain circuits used in natural movements could be used in the development of neuroprosthetics. Previous studies done on this topic have failed to prove that physical movement is not necessary to control a prosthetic device.

“Most brain-machine interface studies have been done in healthy, able-bodied animals,” Jose Carmena, co-director of the UC Berkeley-UCSF Center for Neural Engineering and Prostheses, stated in the release. “What our study shows is that neuroprosthetic control is possible, even if physical movement is not involved.”

The researchers used a brain-machine interface to convert rats’ brain waves from the neurons usually used for whisker twitching into auditory tones. The rats had to modify their thought patterns within the specific brain circuit to raise or lower the pitch of the tone and receive a food reward.

Auditory feedback was used to create an association between the pitch levels and food reward. Over a period of 2 weeks, the rats learned that to receive sugar water, they would have to create a low-pitched tone, and to receive pellets, they would have to create a high-pitched tone. If the neurons in the task were used for their normal function, whisker twitching, there would be no pitch change and no reward.

The rats were able to control the amount of pellets and sugar water that they received based on their own levels of hunger and thirst, demonstrating that their actions were intentional and goal-directed, rather than habitual. The researchers hope that these findings can be translated into creating more natural prostheses.

“What we hope is that our new insights into the brain’s wiring will lead to a wider range of better prostheses that feel as close to natural as possible,” Carmena said. “[The results] suggest that learning to control a brain-machine interface, which is inherently unnatural, may feel completely normal to a person, because this learning is using the brain’s built-in circuits for natural motor control.”

The study was published in the advanced online publication of the journal Nature.

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