However, up until now it has been disputed as to whether the brain structure led people to become London cabbies or whether the brain structure changed as a result of their intensive training (which requires rote memorization of essentially the entire street map of one of the largest and least-organized cities in the world). Well, this latest study answers that. MRI scans before and after the training show that the regions of the brain substantially grow as a result of the training, that they're quite normal beforehand.
The practical upshot of this research is that — even for adult brains, which aren't supposed to change much — what you learn structurally changes your brain. Significantly."