NERVE CELLS – LIFE SPAN [ THE AMAZING BRAIN ]
Amazingly, the cells that perform the complicated ballet of electrochemical transmission can live more than a hundred years, but they do not get replaced like most other body cells. Except for the hippocampus and the olfactory bulb, where new neurons have been shown to grow from stem cells, the neurons a person has at birth are all he or she will ever have.
During the busiest times of neuron generation in the developing brain of a fetus, about a quarter million neurons are created every minute. They start from precursor cells and then migrate and differentiate.
When a neuron in the central nervous system dies or its long fibers are cut, it does not regenerate. Medical science currently has no cure for catastrophic nerve injuries of the spinal cord, and once a major communication line to or from the brain has been cut, it cannot be repaired. But new research with neural stem cells suggests neurons may yet be coaxed into regeneration.
Research into how to regenerate nerve tissue after injuries like transections, a complete severing of the spinal cord, owes a great deal to the late actor Christopher Reeve. In 1995, Reeve shattered a cervical vertebra in a horseback riding accident and became paralyzed from the neck down, a condition known as quadriplegia. The injury was not quite a transection—he eventually regained some sensation—but nevertheless proved devastating. His public appearances in a wheelchair until his 2004 death drew attention to spinal injuries and ultimately raised millions of dollars to help seek a cure for nerve damage.