The other day someone asked about the study of London Taxi Drivers’ brains and what it really showed. The short answer is that the brain appears to contain a GPS (Global Positioning System) located in the hippocampi (two of them), part of the brain’s limbic system or second functional layer. The hippocampi contain built-in maps, compasses, grids and so on. Researchers used structural MRIs of the brains of humans with extensive navigation experience (e.g., licensed London taxi drivers), then analyzed and compared them with those of control subjects who did not drive taxis. The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects. One conclusions was that currently, London taxi drivers, who have to know their way around hundreds of thousands of winding streets, are believed to have the most refined and powerful brain GPS yet identified, strengthened from years of experience. (see link below).