I used to work in a physics lab where I was in charge of regularly transferring liquid helium from a tank to a susceptometer (an instrument often used for superconductivity studies). One day, the helium transfer line that I was holding sprung a leak and I froze a good portion of my finger before I was able to stop that leak. Over the days that followed, I could not feel my finger at all and assumed that the nerve damage was permanent. However, as those days turned into weeks and my previously frozen finger healed, I started regaining sensation. After a month had passed, my finger looked and felt just like it had before the helium freeze.
Neurogenesis (the creation of new neurons) is widely accepted as fact for the peripheral nervous system; for example, the nerves in my finger grew back even though I had lost them to frostbite. However, there is the widespread belief that neurons in the central nervous system (CNS) are static and do not multiply after adulthood. The evidence for such belief is everywhere, from spinal cord injuries that result in permanent lifelong paralysis to neurodegenerative conditions such as multiple sclerosis. However, like many widespread beliefs that are simply assumed to be true, nature always finds a way to foil our best laid plans. Continue reading “How Exercise Can Grow Your Brain”