A Columbia University study in mice hints at new, activity-centred treatment strategies which could speed recovery times after brain damage or stroke, researchers say.

They focused their study on the part of the cerebral cortex called the barrel cortex, which, in mice, is thought to be critical for sensing and analysing signals during “whisking” (moving whiskers to strike objects).

“Mice use whiskers to sense their surroundings the way we use our fingers,” explains researcher Y. Kate Hong. Mice were placed in a dark box and trained to search for a nearby object with their whiskers.

When the mice detected the object, they pulled a lever with their paw to dispense water as a reward. Conventional wisdom suggests this kind of detection depends almost entirely on a functioning sensory cortex — in this case, the barrel cortex.

To test this, researchers used laser light to temporarily turn off barrel-cortex cells. As expected, animals had difficulty whisking while the cells were turned off. And when the team then permanently removed their barrel cortex, the animals could not perform the task the next day.

But on day two, the animals’ performance suddenly recovered to original levels. “This came as a huge surprise, since it suggested that tactile sensation, such as whisker-based touch, may not completely rely on the cortex,” says Hong. “These findings challenge the commonly held, cortex-centric view of how the brain drives touch perception.”

The researchers suspect that other, more primitive brain regions may be involved to a greater degree than previously known. “Rather than being confined to one particular brain region, sensory information is distributed across many areas,” says Hong.

“This redundancy allows the brain to solve problems in more than one way — and can serve to protect the brain in case of injury.”

But to recover, did the animals simply need a day of rest, or did they need to be re-exposed to the task? To find out, the team performed another round of experiments, with one key difference: they let the mice rest for three days before re-exposing them to the task.

This time, the mice showed incomplete rehabilitation. While they did eventually regain some sensation, they recovered more slowly than the first set of mice. The key to a speedy recovery appeared to lie in re-engaging with the task early — not the passage of time. As to why all mice perform so poorly during the first 24 hours, regardless of what they do? The reason may lie in the disturbance that the brain has just experienced.

“The cortex connects to almost every other structure in the brain, so manipulating it may temporarily disrupt connected structures — in essence shocking those areas that would normally enable a behaviour,” researchers explained.

They caution that their research on rodents cannot be directly applied to human beings. But they hope their findings will be further explored by neurologists looking to improve recovery times for their patients.