If you prac­tice biceps curls at the gym, you will get big­ger mus­cles that are also stronger. So far, the same seemed true for the brain. Thanks to neu­ro­plas­tic­ity, prac­tice trig­gers neu­ronal and synap­tic growth (i.e., brain vol­ume growth), which cor­re­lates with bet­ter per­for­mance. In this fas­ci­nat­ing Sci­en­tific Amer­i­can arti­cle we learn that as the brain mas­ters a new skill, some brain areas do get big­ger but even­tu­ally shrink back to nor­mal! The per­for­mance gain acquired through prac­tice stays present, in spite of the shrinkage.

Study­ing the audi­tory cor­tex of rats, they found that the expan­sion of a ‘skill-specific’ brain area with train­ing is only short lived, even when changes in abil­ity are long lasting.

So what does change? Although newly learned per­cep­tual skills don’t show up in a bird’s eye view of the cor­tex, they must have some neu­ro­bi­o­log­i­cal basis. Kil­gard sug­gests that learn­ing prob­a­bly results from a few par­si­mo­nious tweaks at a more micro­scopic level, involv­ing rel­a­tively small num­bers of neu­rons and synapses.

Kil­gard spec­u­lates that the expand­ing cor­ti­cal map is like a search com­mit­tee. It’s gen­er­at­ing a huge range of can­di­date solu­tions to a prob­lem the brain has been tasked with, but doesn’t yet know how to solve. […] Once a good solu­tion is found, the search com­mit­tee is dis­banded. Effi­cient changes that impart skill are retained, and the non-meaningful changes are win­nowed away as the map shrinks.

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