“Experiments show that just as the brain can build new or stronger circuits through physical or mental practice, those circuits can weaken or dissolve with neglect. “If we stop exercising our mental skills,” writes Doidge, “we do not just forget them: the brain map space for those skills is turned over to the skills we practice instead.”36 Jeffrey Schwartz, a professor of psychiatry at UCLA’s medical school, terms this process “survival of the busiest.”37 The mental skills we sacrifice may be as valuable, or even more valuable, than the ones we gain. When it comes to the quality of our thought, our neurons and synapses are entirely indifferent. The possibility of intellectual decay is inherent in the malleability of our brains. That”