Exercise Builds Brain Cells

OK, so far researchers know only that exercise builds brain cells in mice, but at least one experiment suggests that it could do the same for humans. The Scientific American reports that Dr. Scott Small, a neurologist at Columbia University Medical Center in New York, and Fred Gage, of the Salk Institute in La Jolla, California worked together on research that indicated that, when mice exercised, they grew new brain cells in a brain region called the dentate gyrus, a part of the hippocampus that is known to be affected in the age-related memory decline that begins around age 30 for most humans.
The researchers then moved on to human subjects. Sciam reports that  they recruited 11 healthy adults and made them undergo a three-month aerobic exercise regimen. They did MRIs of their brains before and after the three month period, and they also measured the fitness of each volunteer by measuring oxygen volume before and after the training program.  Small and Gage found that exercise generated blood flow to the dentate gyrus of the people, and the more fit a person got, the more blood flow the MRI detected. The two researchers reported that "the remarkable similarities between the exercise-induced cerebral blood volume changes in the hippocampal formation of mice and humans suggest that the effect is mediated by similar mechanisms."  Read more.