Via Flickr/Johann Piber
Those whiskers may have to go. Washington University grad student Andrew Kraft and senior author Dr. Jim-Moo Lee just released a study showing that cutting off sensory input to a healthy part of the brain can speed recovery from a stroke.
Because mice receive sensory signals through their delicate whiskers, the researchers did a little barbering on half of its study participants, after inducing strokes in the part of the brain that controlled their right forepaw.
All of the mice reacted initially by favoring their left forepaw. But four weeks later, the dewhiskered mice were back to using their right forepaws, and by eight weeks, they were just as dexterous with that forepaw as with the left. The mice with intact whiskers showed zero improvement at four weeks and only partial recovery at eight weeks.
At the trial's end, researchers mapped their tiny subjects' brains. In the dewhiskered mice, the area that receives sensation from the whiskers had neatly taken over the function of controlling the right forepaw. In their less lucky colleagues, forepaw control had popped up in any of several nearby spots, but in a more random and far less efficient way.
Now everybody's whiskers have grown back. Do the trimmed ones work as well as ever? There's no way to ask, but Lee's pretty confident that they do. "The part of the brain that controls fine finger movements is unusually large in musicians," he points out, "and the part for navigation is enlarged in taxi drivers. Developing those skills doesn't cause musicians and taxi drivers to lose any other abilities. They're probably just using their brains more efficiently."
The hope for people recovering from strokes is obvious. Humans share more DNA with mice than with any other animal. Because the neurological map in the human brain correlates so well with the geography of the body--the part of the brain that controls the arm, for example, is adjacent to the part that controls the shoulder--we could immobilize the shoulder if a stroke had sapped control of our arm. The whiskers principle holds: Cutting off neuronal signaling to an adjacent brain area makes it easier for the brain to remap itself. Rather than throw more input at the brain as we try to retrain it, we can make its job easier by clearing space.
