"I am staring down a microscope in the most advanced lab I have ever visited…looking at living, human neuronal stem cells in a petri dish…The neuronal stem cells I see are vibrating with life. They are called neuronal stem cells because they can divide and differentiate to become neurons or glial cells, which support neurons in the brain. The ones I am looking at have yet to specialize, so they all look identical. Yet what stem cells lack in personality, they make up for in immortality. For stem cells don’t have to specialize but can continue to divide, producing exact replicas of themselves, and they can go on doing this endlessly without any signs of aging. For this reason stem cells are often described as the eternally young, baby cells of the brain. This rejuvenating process is called neurogenesis, and it goes on until the day that we die."