By studying hand motions, bioengineer is creating instruction manual to help repair a broken-down brain

February 6, 2013

(Medical Xpress)—”When you grab a cookie and want to break off a piece with a chocolate chip,” says Maurice Smith, balancing a crumbly bit between two of his fingers, “your brain must represent that action plan extrinsically, as it is an activity based in the world.”

The cookies are on hand to celebrate the bioengineer’s birthday in his lab at 60 Oxford Street, a white squat building located on the northernmost edge of the Harvard campus. A half moon of chocolate cake with a line of colored candles still intact also sits nearby.

Gesticulating with the cookie, Smith, Associate Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences (SEAS), further teases out the intricacies of motor memory.

“An intrinsic representation is one that’s body-based and procedural. It relates to the complex series of muscle and joint movements your body has to make to complete a task,” Smith says.

“When I first had the thought to grab the cookie and rip off a chunk with a chocolate chip, my body responded appropriately,” he notes.

Understanding the way the brain represents extrinsic and intrinsic actions, and the relationship between the two, has been of great interest to researchers who seek to understand motor control and motor learning—or, put simply, how we learn to move.

Just a few months ago, Smith and his colleagues in the Neuromotor Control Lab laid out a generalizable theory about how the brain encodes such motor memories. Writing in the Journal of Neuroscience, they showed that units of motor memory are not so binary after all, but instead a mixture of both the intrinsic and the extrinsic.

Read more: By studying hand motions, bioengineer is creating instruction manual to help repair a broken-down brain — Medical Xpress.

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