X-Message-Number: 11311 Date: Tue, 23 Feb 1999 15:54:18 -0500 From: Jan Coetzee <> Subject: Exercise: brain cells Exercise, variety stimulate brain cells NEW YORK, Feb 22 (Reuters Health) -- Studies in mice suggest that vigorous exercise may stimulate the development of new cells in the area of the adult brain involved in learning. The study findings also suggest that exercise and interesting, varied surroundings may prolong the life of these cells. These results indicate that the replacement of cells in this area, called the hippocampus, ``may be regulated by experience,'' according to Dr. William Greenough and colleagues at the University of Illinois in Urbana. Their comments come in response to two studies published in the March issue of the journal Nature Neuroscience. Until recently, scientists believed that the number of mammalian brain cells remained static once the brain matures. But researchers have since discovered cell generation in the brains of adult mice, birds, and monkeys. This cell regeneration seems to be limited to the brain's hippocampus, a center for memory and learning. Both studies sought to determine the living conditions most conducive to this regenerative process. In one study, investigators at The Salk Institute for Biological Studies in La Jolla, California, used fluorescent staining techniques to identify newly-formed brain cells in the hippocampi of mice. They placed these mice in various living environments, and had them perform specific tasks. The authors found that ``voluntary exercise in a running wheel increased cell proliferation,'' doubling the number of surviving newborn cells in the hippocampus. The team's findings appear to fit with what experts know about the hippocampus. In their commentary, Greenough and his colleagues speculate that ``intense exercise in a natural environment may be associated with a need for increased navigation skills.'' The hippocampus is thought to be the 'control center' for the learning processes involved in understanding and navigating the physical world. In a second study, researchers at Princeton University and Rutgers University, both in New Jersey, used similar methods to study new brain cells in mice exposed to various living conditions. They report that ``environmental complexity increases the number of adult-generated hippocampal neurons in... mice.'' In other words, mice exposed to living spaces filled with interesting, varied objects and stimuli had higher cell regeneration than rodents placed in stark, empty cages. The New Jersey researchers theorize that ``learning about space... has a highly trophic (growth-inducing) effect on adult generated hippocampal neurons.'' And they point out that immature neurons are especially suited to make the quick, novel connections necessary in spatial learning. Greenough and colleagues speculate that the hippocampus has developed the ability to regenerate in order to aid the cerebral cortex ``by adding neurons that can deal with new information (while) deleting those that encode obsolete information.'' SOURCE: Nature Neuroscience 1999;2:203-205, 260-265, 266-270. J.C. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11311