Conventional wisdom advocates for rest after suffering an injury. Now researchers have discovered that activity — not rest — helps the brain recover from trauma in mice. The finding suggests that challenging the brain early after damage can speed up healing.

“Lengthy rest periods are supposed to be key to the brain’s healthy recovery, but our study in mice demonstrates that re-engaging the brain immediately after injury can actually be more helpful than resting it,” study lead Randy Bruno, a neuroscientist at Columbia University’s Zuckerman Institute in New York City, said in a statement.

The results were “completely unexpected,” he added.

Touchy Sensations

Bruno started the research hoping to untangle how the brain detects and processes the sense of touch. To find out, the researchers trained thirsty mice to get water by releasing a lever when they felt a pole brush their whiskers in the dark. The team then used optogenetics to turn off neurons in the barrel cortex, a brain region that processes touch information in whiskers.

Without these cells operating as normal, the rodents’ performance completing the task fell. Follow-up experiments revealed inactivating the brain cells had impaired, but not destroyed, the animals’ abilities to detect touch through their whiskers.

Since the mice could still sense touch, the scientists thought the optogenetic set up hadn’t completely turned off all of the intended cells in the barrel cortex. So, they removed the brain region from the trained mice and after a day of rest challenged the animals to another round of water retrieval. At first, the brain-damaged mice did about as well as the mice that had had their neurons shut off. But in a follow up session, mice that lacked a barrel cortex suddenly performed as well on the task as they had before scientists removed the brain region. The touch-sensing capacity of their whiskers recovered too, researchers report today in the journal Nature.

Use It Or Lose It

To determine whether the strain of having to complete the detection task or the mere passage of time prompted the mice’s recovery, the researchers repeated the experiment. This time they gave the mice three days’ rest between brain injury and re-testing. In their first trial, the rested mice did not do well on the task, but recovered after subsequent testing sessions. The results suggest activity, not rest, leads to recovery.

“We tend to immobilize people when they’ve suffered a stroke; the recovery of seemingly simple tasks — walking, grasping — can be a long road,” Bruno said in a statement. “Our findings suggest that maybe in some cases, patients could be reintroduced to these activities much earlier in order to speed recovery.”