From this New York Magazine article Why Running Helps Clear Your Mind -- Science of Us:
Regular exercise improves our ability to think and remember through the creation of new brain cells, a process known as neurogenesis.
From this NY Times article, How Testosterone May Alter the Brain After Exercise:
“A new study found that male sex hormones surge in the brain after exercise and could be helping to remodel the mind”.
They tested to see if rats produce the testosterone in the brain by shutting off production in the testes (castration). Further, some of the animals also were injected with a drug that negated the effects of testosterone produced by the brain. Some rats were not altered. They were then divided into groups, sedentary and active rats. The active rats exercise on treadmills for two weeks; the sedentary rats played video games (not really).
Quote from the article:
In a study two groups took a memory quiz. Then one group cycled to exhaustion in 30 minutes and the other group sat there. Their memories were then retested. The result:
“The exercised volunteers performed significantly better on the memory test than they had on their first try, while the volunteers who had rested did not
improve” – quote from the NY Times article How Exercise Benefits The Brain.
They also took blood samples throughout the experiment. They found that: “The cyclists had significantly higher levels of a protein known as brain-derived neurotrophic factor, or BDNF, which is known to promote the health of nerve cells. The men who had sat quietly showed no comparable change in BDNF levels.”
From the article Get Moving for a Health Brain in the September 2013 AARP Bulletin these quotes:
The latest research shows that cognitive decline is not inevitable…the brain continues to make new neurons and fine tune neural connections as we live…Aerobic exercise jumps-tarts that process and slashes your lifetime risk of Alzheimer’s’ in half and general dementia by 60 %.
Exercise boosts the flow of blood to the brain, spurring the release of what has been dubbed Miracle-Gro for the brain – brain-derived neurotrophic factor (BDNF). This chemical stimulates the formation of new neurons in the hippocampus, the area involved in memory, learning and the ability to plan and make decisions. BDNF also repairs cell damage and strengthens