“Exercise doesn’t make you smarter…it just makes you normal.” This great quote from John Medina in Brain Rules illustrates the essential role that physical activity plays in maintaining a sharp mind. The brain is best at solving problems related to surviving in an unstable environment, and to do so in nearly constant motion. This is what the brain did for virtually all of human history until we engineered the need for physical activity out of everyday life
Rush to the Head
Exercise literally increases the blood volume in a region of the brain called the dentate gyrus, a vital part of the hippocampus. Exercise also stimulates BDNF, a protein which exerts a fertilizer-like growth effect on certain neurons. This protein keeps existing neurons young and healthy, rendering them much more willing to connect with one another. It also encourages neurogenesis, the formation of new cells in the brain. The cells most sensitive to this are in the hippocampus, inside the very regions deeply involved to human cognition and memory.
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Stress, lack of exercise, and junk food harms your brain. Stressed brains don’t learn the same way. The hormones released in response to stress are meant for immediate danger response, not chronic stress. Chronic stress makes adrenaline scar blood vessels while cortisol damages the cells of the hippocampus. Since exercise influences metabolism, it serves as a powerful way to influence synaptic function, and thus the way we think and feel.
Jonathan Ross http://blogs.discovery.com/jonathan_ross