Exercise Creates new Brain Cells
Researchers at Princeton University recently made a remarkable discovery about how neurons respond differently to stress than to inactivity. Scientists have known for some time that exercise stimulates the creation of new brain cells (neurons) but not how, precisely, these neurons might be functionally different from other brain cells.
Exercise creates a Calm Brain
Preliminary results presented at the annual meeting of the Society for Neuroscience in Chicago, showed that experimental rats had created, through running, a brain that seemed biochemically, molecularly, calm when presented with stressful situations.
How Exercise Remodels the Brain
For years, it has been a given that exercise enhances mood. But how exercise might directly affect mood and anxiety — psychological states — was unclear. Now, thanks to improved research techniques scientists are beginning to tease out how exercise remodels the brain, making it more resistant to stress. At the University of Colorado, Boulder, scientists have examined the role of the neurotransmitter serotonin, considered to be the “happy” brain chemical. The view of serotonin has been undermined by this and other research. In those experiments, rats exposed to a laboratory stressor, showed increased serotonin activity in their brains. But those rats, that had run for several weeks before being stressed, showed less serotonin activity and were less anxious and helpless despite the stress.
Moderate Exercise reduces Effects of Oxidative Stress
Researchers have looked at how exercise alters the activity of the dopamine neurotransmitter in the brain, and on the antioxidant powers of moderate exercise. Anxiety in people has been linked with excessive oxidative stress, which can lead to cell death, including in the brain. Moderate exercise, appears to reduce the effects of oxidative stress. In an experiment at the University of Houston, rats whose oxidative-stress levels had been artificially increased were extremely anxious when faced with unfamiliar terrain during laboratory testing. But rats that had exercised, even if they had received the oxidizing chemical, were relatively calm under stress. When placed in unfamiliar circumstances, they didn’t run and hide, like the unexercised rats. They casually explored.
Positive Stress of Exercise
“It looks more and more like the positive stress of exercise prepares cells and structures and pathways within the brain so that they’re more equipped to handle stress in other forms,” says Michael Hopkins, affiliated with the Neurobiology of Learning and Memory Laboratory at Dartmouth, who has been studying how exercise differently affects thinking and emotion. “It’s pretty amazing, really, that you can get this translation from the realm of purely physical stresses to the realm of psychological stressors.”
Don’t Quit, Keep Exercising
The stress-reducing changes evoked by exercise on the brain don’t happen overnight. In the University of Colorado experiments, rats that ran for only three weeks did not show much reduction in stress anxiety, but those that ran for six weeks did. “Something happened between three and six weeks,” says Benjamin Greenwood, a researcher in the Department of Integrative Physiology at the University of Colorado. Dr. Greenwood added that it was “not clear how that translates” into exercise advice for humans. We do not know how intense the exercise needs to be. Dr. Greenwood says, the lesson is “don’t quit.” Keep running or cycling or swimming or doing Yoga. You may not feel a magical reduction of stress after your class, if you haven’t been exercising. But the molecular biochemical changes will begin, Dr. Greenwood says. And eventually, he says, they become “profound.”
See the New York Times