Jog For Mental Health

A new study recommends that people who want to jog their minds literally put one foot in front of the other.

Researchers at the Salk Institute for Biological Sciences say laboratory mice exposed to the physical stimulation of running were better at mental tasks than mice that did not exercise.

"It does seem physical activity is beneficial for mental function," said Henriette van Praag, a Salk scientist who led the study.

Mice that exercised grew small amounts of new cells in parts of the brain that are important for learning and memory, and those areas seemed to function more efficiently, the study showed.

The study, undertaken in the laboratory of Fred Gage, is part of a string of experiments that may prove whether exercise could improve recovery from brain injuries or hold off mental declines associated with dementia or Alzheimer's.

The past experiments showed that the brains of adult mice and even people could generate new brain cells called neurons from latent, undifferentiated cells in the brain.

"What I find most exciting is that, taken together, the studies suggest that throughout one's life one's behavior can change the structure of the brain, and that these changes can in turn affect how we behave in our environment," Gage said.

In the latest research, reported previously in the Proceedings of the National Academy of Sciences, scientists wanted to test how newly formed neurons in mice affected mental function and cognitive ability.

They tested the ability of the mice to learn spacial relationships by placing the animals into a water-filled maze and timing how long it took them to learn the new environment and find a platform they could climb onto and rest.

Most mice from a group that had been running about three hours a day for five weeks could find the platform in about 16 seconds after three days of trials in the maze.

Meantime, many of the mice that had been sedentary in previous weeks took about 25 seconds to complete the same task.

All the mice in the study were genetically identical.

Though even the sedentary mice grew some new brain cells, an autopsy of the mice's brains showed that the exercise group had more than twice the number of new neurons.

Moreover, the neurons in the hippocampus' dentate gyrus region, where the new cells grew, all generally displayed a greater sensitivity to being stimulated by surrounding neurons.

Researchers said that makes it easier and more efficient for the neurons to communicate.

"It does suggest these newborn cells do have a functional role in the adult brain," van Praag said.

The researchers say it is not yet clear whether the small amount of newly generated cells account for the increased learning capacity, or whether the exercise prompts existing cells to function at a higher level.