Posted on Aug 15, 2013, 6 a.m.
Physical activity reorganizes the brain so that its response to stress is reduced and anxiety is less likely to interfere with normal brain function.
A discrepancy in research related to the effect of exercise on the brain has existed: namely, that exercise reduces anxiety while also promoting the growth of new neurons in the ventral hippocampus. Because these young neurons are typically more excitable than their more mature counterparts, exercise should result in more anxiety, not less. Timothy Schoenfeld, from Princeton University (New Jersey, USA), and colleagues have revealed that exercise also strengthens the mechanisms that prevent these brain cells from firing. Employing a mouse model, the team observed that when mice allowed to exercise regularly experienced a stressor — exposure to cold water — their brains exhibited a spike in the activity of neurons that shut off excitement in the ventral hippocampus, a brain region shown to regulate anxiety. Further, the research team pinpointed brain cells and regions important to anxiety regulation that may help scientists better understand and treat human anxiety disorders. The researchers found that running prevents the activation of new neurons in response to stress. In sedentary mice, stress activated new neurons in the hippocampus , but after 6 weeks of running, the stress-induced activation of both new and mature neurons disappeared. Taken collectively, the study authors submit that their data suggest that exercise “improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus.”
Schoenfeld TJ, Rada P, Pieruzzini PR, Hsueh B, Gould E. “Physical exercise prevents stress-induced activation of granule neurons and enhances local inhibitory mechanisms in the dentate gyrus.” J Neurosci. 2013 May 1;33(18):7770-7.