They were then asked to quit juggling oompletely, and three months later the enlarged areas of the cortex had started to shrink. The 2000 study, also done with MRI scanners, found a change in the O shape of the cabbies' hippocampus, the brain module where new memories of place are stored. Both studies show how malleable the brain is under training, a finding O already hinted at by the brain's own internal representation, or mapping, of body parts. The brain has about 100 billion neurons, each of which makes on O average 1000 connections with others, for some 100 trillion interconnections in all, none of them color coded.​