[ale] Hardening of the brain

[Dow Hurst]

Myelin is the neural casing that gets destroyed in MS.

http://en.wikipedia.org/wiki/Myelin

The main consequence of a myelin layer (or /sheath/) is an increase in 
the speed at which impulses 
<http://en.wikipedia.org/wiki/Action_potential> propagate along the 
/myelinated/ fiber. Along /unmyelinated/ fibers, impulses move 
continuously as waves, but, in myelinated fibers, they hop (or 
"propagate by saltation 
<http://en.wikipedia.org/wiki/Saltatory_conduction>"). Myelin increases 
resistance by a factor of 5,000 and decreases capacitance by a factor of 
50. Myelination also helps prevent the electrical current from leaving 
the axon and causing a short-circuit 
<http://en.wikipedia.org/wiki/Short-circuit> in the brain. When a 
peripheral fiber is severed, the myelin sheath provides a track along 
which regrowth can occur. Unmyelinated fibers and myelinated axons of 
the mammalian central nervous system do not regenerate.


The trick to staying limber mentally is challenging your brain with new 
ideas that force you to think differently and learn how to do new 
things.  Repetitive exercises will help you get better at some process 
but it is the new neural connections and brain growth due to new ways of 
thinking and doing that keep a brain snappy.  Plus, good genes are hard 
to beat!!  Let's hope we are all from the deep end of the gene pool!
Dow