Contrary to popular belief, we don't have a limited supply of brain cells. Sure, the majority of them grow early in life, but some areas of the brain continue to grow them into adulthood and beyond - a process called neurogenesis. The hippocampus is one of these areas, and it's also among the most important areas of the brain, playing roles in memory, emotion, and learning. But as we grow older, a number of factors compete with neurogenesis and kill brain cells.
http://www.msn.com/en-us/health/medical/5-ways-youre-killing-your-brain-cells/ar-AA9SWiB#page=1
http://www.msn.com/en-us/health/medical/5-ways-youre-killing-your-brain-cells/ar-AA9SWiB#page=1
