Despite the advent of Google Maps, black cabbies on the streets of London still rely on their working memory of its 58,000 streets. The University College London's Spatial Cognition Group, interested in understanding more about Alzheimer's disease, is taking an interest in studying London's black cabbies. Professor Eleanor Maguire, a neuroscientist, and the team scanned the brains of 30 drivers while testing their navigational skills. What they found was that the area involved with spatial recognition, the hippocampus, is particularly large. "Their hippocampus appears to get bigger the more years they put into the job," says research lead, Professor Hugo Spiers. "That's really interesting for dementia research, because it's precisely the part of the brain that declines in size with Alzheimer's disease. Maybe there's something very protective about working out your spatial knowledge on a daily basis, like these guys do."