Yes, what is lost does not heal. Science refers to the process as Neuroplasticity (or brain plasticity).

My brain scan shows evidence of a prior injury to the brain. I interpret that to mean brain damage. However, the good news is that when you excercise your brain it responds by adapting. At least, that is how I understand it.

Another quote:
Brain plasticity is a common term used by neuroscientists, referring to the brain's ability to change at any age – for better or worse.

brainHQ from Posit Science
http://www.brainhq.com/brain-resourc...ain-plasticity

I interpret the words 'better or worse' to mean, 'use it or lose it'. Your brain can and will adapt if you give it the chance.
Jamie