Have you ever wished you could turn up the gain on your brain, getting just a little more juice right before a tough exam or a big experiment? Scientists have now managed such a feat in rats, boosting their performance on a memory test by electrically stimulating a region deep inside their brains. The technique is unlikely to ever be performed on healthy humans, but the researchers say it may prove useful for people who've suffered strokes or other brain injuries.
Deep brain stimulation has been used for years to treat people with Parkinson's disease. More recently, researchers have reported encouraging results for treating depression (Science, 4 March 2005, p. 1405), and just last week a team reported a promising case study in which a man in a minimally conscious state recovered some mobility and responsiveness (ScienceNOW, 16 October). Yet very little is known about how deep brain stimulation works.
That's changing through work on lab animals. A team led by neurologist and neuroscientist Daniel Herrera at Weill Medical College of Cornell University in New York City implanted electrodes into the central thalamus of rats. This brain region is thought to help mediate arousal and is the region surgeons targeted in the minimally conscious patient. After stimulating the rats' central thalamus for 30 minutes, Herrera and colleagues found that two genes--one linked to neural activity and the other linked to cellular mechanisms of learning--had become more active in the rats' brains, including in the cerebral cortex and hippocampus. The stimulated rodents also explored more than unstimulated rats did and performed substantially better on an object-recognition test, Herrera and colleagues report online this week in the Proceedings of the National Academy of Sciences.
"It's a significant finding," says Rodolfo Llinas, a neuroscientist at New York University. But don't call your neurosurgeon just yet. Herrera cautions that more work is needed to determine how long the benefits last and what the side effects are. Besides, he adds, the ultimate goal isn't to make healthy people smarter, it's to help neurological patients. Those most likely to benefit from the procedure are stroke or head-injury patients, whose brain damage is more stable than that of someone with a progressive disease such as Alzheimer's, Herrera says.