Exercise and the Birth of New Neurons

It took decades of research to persuade scientists to give up their long-held belief that new neurons could not be formed in the brains of adults, but there is no longer any doubt about it.
It is now well-established that strenuous physical exercise stimulates the birth of new neurons in part of the brain that is critical for memory, the hippocampus.
Immature non-neuronal cells in the adult brain (glia) respond to protein growth factors that are generated in the body during robust physical activity. These growth factors stimulate the mother cells to spawn new neurons in the hippocampus. Amazingly, these nubile neurons then migrate through brain tissue to find their proper place in the neural circuitry. Even more remarkable, new research proves that the new neurons are then able to wire themselves into the existing network of connections to boost performance in memory, just like adding RAM chips does for a laptop. But why? Why should pumping muscles build more brain cells?

In the beginning human activity was be divided into two states: lounging and looking for food. Searching for food was the intellectual arena of cognitive challenge. The purpose of memory back then, as it is today, is to integrate novel information that is likely to be important to our survival in the future. This, the scientists suggest, is why the body hatches new neurons in the memory region of the brain when we exercise -- to better equip us for the cognitive demands of the excursion.

Building brains by exercise has been shown to provide animals with an increased cognitive reserve, meaning that after brain injury or disease that kills or damages healthy neurons, animals that have been forced to do reps on the exercise wheel before a brain injury, do far better in recovering. The animals forced to work out also have much slower cognitive decline in aging compared to sedentary cage-mates, because the loss of brain cells is a normal process of aging.

Surprisingly, the same drugs used to treat chronic depression have been found to stimulate the birth of new neurons in the hippocampus. This ancient biological connection between muscle and brain can account for how pumping iron could benefit our mental health as well as our cognitive health.....

Gerd Kempermann and colleagues at Stanford, the University of Zurich and Dresden, Germany, their recent paper published in the journal "Frontiers in Neuroscience."

http://www.livestrong.com/article/118785-exercise-brain-cell-growth/

Mechanism of Exercise-induced Neurogenesis

Exercise increases growth factors in the brain, such as vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF), according to a 2007 literature review by Henriette van Praag. Both factors make it easier for new neurons to grow VEGF by increasing blood vessels and blood flow to new neurons, and BDNF by increasing the rate of neurogenesis.