The discovery that the adult brain is capable of a process called neurogenesis, or producing new neurons, is perhaps one of the most exciting neurological revelations of the 21st century. Until only a few decades ago, it was accepted as medical fact that the brain cells you were born with were all you had to work with for the rest of your life. Now we know that the human brain produces several thousand new neurons each day and is remarkably resilient. Scientists have discovered several important factors, including exercise, that play an essential role in neurogenesis and overall brain health.
About Neurogenesis
The past few decades of research have revealed several important principles of neurogenesis. Scientists have discovered where in the brain neuronal birth takes place, uncovered several factors that seem to influence neuronal birth and survival and have some idea how the new neurons become assimilated into the working brain. Research as of 2011 suggested that the most important site of neurogenesis is a part of the brain called the dentate gyrus of the hippocampus. Here, several thousand new neurons are produced everyday in the adult brain. However, not all of these neurons survive. The chances of the new neurons surviving seems to be largely influenced by variables like hormones, environmental stimulation, learning and exercise.
Importance
Since neurogenesis is still a relatively recent discovery, the exact reason for neuronal proliferation in the adult brain is not well understood. However, the implications of this discovery are exciting. For instance, we know that the hippocampus is largely responsible for learning and memories. As we age, the brain -- including the hippocampus -- begins to shrink. It is possible that neurogenesis plays a role in staving off memory loss and other age-related diseases like Alzheimer's and dementia. Indeed, a number of researchers have found that individuals with Alzheimer's have smaller hippocampi compared to the rest of the population.
Exercise
Researchers have tried to identify factors that influence neurogenesis using animal models. For instance, one study showed that mice who exercised regularly on a running wheel had twice the number of new neurons as their sedentary counterparts. Researchers at Columbia University were able to expand upon existing research to study humans using magnetic resonance imaging. The researchers found that middle-aged people who exercised for one hour per day, four days a week for three months showed similar hippocampal changes as those seen in animal models. Although the technique developed by scientists at Columbia University is not yet refined enough to definitively implicate neurogenesis in the hippocampal changes, their results are promising.
Benefits
Although neurogenesis is not well understood, research supports the idea that regular exercise is good not only for your body but also for your mind. Some studies suggest that endorphins, chemicals produced while exercising, play a role in neuronal proliferation. Other studies suggest that increased levels of neuronal growth factor are stimulated by regular exercise and serve to promote neurogenesis and protect existing neurons. Whatever the cause, now may be the time to consider exercising to protect your brain and memory. Consult your physician before beginning an exercise program.
References
- Wessley College Biology Department: Neurogenesis; March 2005
- The Dana Foundation: Move Your Feet, Grow New Neurons? Exercise-Induced Neurogenesis Shown in Humans; Brenda Patoine; May 2007
- New York Times: Lobes of Steel; Gretchen Reynolds; August 2007
- Society for Neuroscience: Adult Neurogenesis; June 2007
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