At his lab, Frostig had long noticed that a rich sensory environment appeared to make rats not only happier but much healthier. Studying models of stroke in rats, Frostig sought to mimic the effect of a typical ischemic stroke by tying off the middle cerebral artery, which feeds oxygenated blood to a broad swath of cerebral cortex, and then severing it. When he put these rats back into cold, sterile cages, they developed terrible disabilities, as parts of their oxygen-starved brains died, taking neighboring brain cells with them.
But when these rats went back to a rich environment with toys to play with, tunnels to dig and food to find, even severing one of the brain's most important arteries was not enough to create apparent stroke damage.
This week at the annual conference of the Society for Neuroscience, Frostig and his colleagues presented new research showing the profoundly protective effect of early stimulation in preventing stroke damage. Rats who have had a single whisker stroked for five minutes in the two hours after their middle cerebral artery is severed emerged from the experience completely free of brain damage. In another experiment, rats were treated with intermittent auditory stimulation after the blockage of blood flow to, among other regions, the brain's auditory cortex. Those rats, too, survived their strokes with brain function completely intact.
In both cases, the nature of the stimulus -- tactile and auditory -- corresponded to some part of the brain that was being denied blood flow (the sensory cortex is among the brain regions nourished by the middle cerebral artery).
The purposeful stimulation of those brain regions "induces massive redirection of blood flow that results in reperfusion and therefore protection of the ischemic area," Frostig's group concluded. In other words, when challenged to make sense of some incoming stimulus, parts of the brain cut off from their blood supply somehow signal their urgent need for oxygen and fuel, and blood carrying those requirements finds another route to get there.
When it comes to preventing brain damage from an ischemic stroke (the kind in which blood flow is blocked, representing 88% of all strokes), neurologists say "time is brain": Getting a victim to a hospital for treatment quickly makes it possible to reduce brain damage and disability. But only a tiny fraction of patients -- fewer than 1 in 10 -- get to the hospital in time to get clot-busting medicine that could reduce damage.
Do you know the signs of stroke? See them here. And remember as we ready for the holidays, stroke risk increases when individuals--especially those with high blood pressure--eat too much salty food, consume too much alcohol and are under stress. Learn to recognize the signs and always call 911 immediately if you suspect someone is having a stroke.
So if, immediately after a stroke's onset, a stroke victim's friends, family or first responders could follow a simple strategy to help protect his or her brain cells from dying, that would be very useful. "Anything that would activate neurons in the ischemic area should work," Frostig says.
A few caveats -- and they are major. For starters, this research on rats may not translate to humans at all. If it does, the time frame during which stimulation might be helpful -- whether it must come in the first 15 minutes or the first three hours -- is not known. What is known is that there does come a time -- when the brain is reeling from stroke damage and is trying to recover -- when stimulation would be downright harmful. Research on humans having strokes will be practically and ethically difficult, and will take time and money to do.
Finally, an ischemic stroke can strike anywhere in the brain, and the regions affected are often not known until a CT scan finds the blockage or the damage is done. If the stimulation must be aimed at a part of the brain cut off from its blood supply, then families or emergency medical technicians would be guessing at what stimulation would be most helpful to provide. And the "try anything" approach -- singing, dancing, doing crossword puzzles and giving the victim massages -- might be a little overwhelming.
But the possibilities are tantalizing: a "drug-free, equipment-free and side effects-free treatment" that could be administered before the ambulance even arrives, taking a bite out of the nation's number-one cause of long-term disability.