( Neurobiologists have discovered why the...)Stem cell activity deciphered in the aging brain

The finding also suggests the possibility of treating various neurodegenerative disorders, including Alzheimer's disease, dementia and depression, by stimulating the brain's ability to produce new nerve cells, said senior study investigator Ashok K. Shetty, Ph.D., professor of neurosurgery at Duke University Medical Center and medical research scientist at Durham VA Medical Center.

Results of the study appear online in the journal Neurobiology of Aging. The research was funded by the National Institutes of Health and the U.S. Department of Veterans Affairs.

Previous studies by Shetty and others had demonstrated that as the brain ages, fewer new nerve cells, or neurons, are born in the hippocampus, the brain's learning and memory center. In one study, Shetty and colleagues showed that the production of new neurons in rats slows down dramatically by middle age -- the equivalent of 50 years in humans.

But scientists did not know what causes this decline.

The common assumption had been that the brain drain was due to a decreasing supply of neural stem cells in the aging hippocampus, said lead study investigator Bharathi Hattiangady, Ph.D., research associate in neurosurgery. Neural stem cells are immature cells that have the ability to give rise to all types of nerve cells in the brain.

In the current study, however, the researchers found that the stem cells in aging brains are not reduced in number, but instead they divide less frequently, resulting in dramatic reductions in the addition of new neurons in the hippocampus.

To conduct their census, the researchers attached easy-to-spot fluorescent tags to the neuronal stem cells in the hipp
'"/>

Source:Duke University Medical Center