Adapted from:St. Paul/Minneapolis Pioneer Planet 05/28/00
| In a series of remarkable experiments, scientists are learning how experience can reshape and reorganize your brain, not just as a child but even after you have grown up. This gives hope that HD can be treated in novel ways. |
The realization that the brain is not fixed at puberty, as previously thought, could be good news for victims of injury, stroke or disease.
"It may be possible in the future to bypass a damaged brain area," Dr. Mike Ridding, a neuroscientist at Australia's Adelaide University, wrote in April's Journal of Experimental Brain Research.
The ability to regenerate or grow nerve cells in the brain also could help people who suffer damage to other parts of their central nervous systems, including the spinal cord and nerves leading to bodily extremities.
Eventually, someone like actor Christopher Reeve, who was paralyzed in a fall from a horse, might be able to have his damaged spinal cord repaired.
"The neurosurgeon of the future will have a whole arsenal of tools" to help people whose spinal cords have been crushed or cut, according to Jerry Silver, a neuroscientist at Case Western Reserve School of Medicine in Cleveland. Silver already has managed to regenerate severed nerve fibers in mice and rats.
"Until recently, the prevailing view has been that this kind of regenerative growth is unlikely to occur in adult brains," said Neeraj Jain, a neuroscientist at Vanderbilt University in Nashville, Tenn., who has observed damaged nerve cells growing back in laboratory monkeys.
"We conclude that the adult primate central nervous system is capable of extensive new growth," Jain wrote in last month's Proceedings of the National Academy of Science.
A striking example of the adaptability of the adult brain comes from MRI (magnetic resonance imaging) scans of the brains of London taxi drivers.
A section of the cabbies' brains, called the hippocampus, became enlarged during the two years they spent learning their way around the vast, complicated metropolis. The longer they drove, the more a key portion of the hippocampus expanded, according to Eleanor Maguire, the lead investigator in the study.
Deep inside the brain, between the ears, the hippocampus stores mental maps of places and directions. Neuroscientists say it is the center of a "spatial navigation system" that answers such questions as: "Where am I? Where are other things? How do I get there?"
The navigation system includes special "place cells" and "direction cells" that flicker visibly in MRI images when a research subject tries to find his or her way through a simulated urban environment.
Blind people who read Braille with a fingertip enlarge the section of the brain that receives sensation from that finger, researchers report. Similarly, professional musicians develop extra capacity in the brain's auditory region.
The discovery that the adult brain can be molded by experience has a down side, researchers point out. Stress, injury, disease and even aging can reduce the number of healthy brain cells and weaken memory.
For more information, see the Web site of the Society for Neuroscience: www.sfn.org