Imagine a safe, inexpensive and drug-free way to prevent the long-term brain damage that often follows a stroke. No such treatment exists, but a new study involving rats suggests it might not take much to prime the brain to repair itself in the immediate aftermath of a stroke.
For the rats, the simple act of tickling a whisker was enough to allow the animals to regain full cognitive function after a severe stroke — as long as the treatment was given within two hours.
"We're looking for something that can help people wherever they are and long before they get to the hospital," said UC Irvine neuroscientist Ron Frostig, who presented the findings last week at the annual meeting of the Society for Neuroscience in San Diego.
Almost 750,000 Americans a year suffer from an ischemic stroke, which occurs when a clot blocks blood flow to the brain and starves key areas of the cortex, where memory, attention and language functions are controlled.
Only one treatment is available to limit brain damage from stroke — a clot-busting drug called tissue plasminogen activator, or tPA. But the drug must be administered within 41/2 hours of the start of stroke symptoms. Fewer than 5% of people who have an ischemic stroke are treated with tPA, often because they don't get to the hospital in time.
The UCI study proposes a different avenue for preventing stroke damage. If a clot blocks blood flow along one route, why not encourage those blood cells to find another way to get where they're needed?
"It's like when a major street to your house is blocked and you can't get home," Frostig said in an interview. "You find other streets to use to connect to your street and get back to your house. That is exactly what happens in the brain."
To test their theory, Frostig and his colleagues gave rats the kind of brain injury that mimics an ischemic stroke. Then they intermittently stimulated the whiskers of the rats for 90 minutes. The action mimics the natural whisker motion rats make when they are exploring their environment.
The rats receiving the sensory stimulation recovered normal cognitive function. When the scientists looked at the animals' brains a week later, they saw that blood flow had indeed been rerouted to the damaged area to compensate for the blockage.
However, when the researchers also severed blood vessel connections that were farther away from the clot, the mice did not improve. That suggests that the compensatory blood flow did stimulate recovery.
"The data seem very convincing to me," said Julius Fridriksson, a neuroscientist not involved in the research who studies stroke recovery at the University of South Carolina. "You never reestablish tissue that was lost, but the brain has a way to heal itself and make new connections."
In order to be effective, sensory stimulation has to take place right away — within two hours of the stroke, Frostig said. The rats who received whisker tickles in the first hour improved more than those who were tickled in the second hour. The treatment appeared to work on both young and old rats.
Researchers aren't sure what kind of stimulation could be given to humans that would mimic the whisker tickling. Touching the body in sensitive areas, such as the lips and fingers, is a potential target, Frostig said. It's possible that auditory or visual stimulation might help, too.
"The beauty of this, in my mind, is that you can do it anywhere," Frostig said. "You can start treating a person and maybe save their life."