The famous studies of London’s taxi drivers – showing they have larger hippocampi (the comma-shaped brain structure in the temporal lobes) than controls – have become a staple of undergrad psychology courses and a classic example of how your brain changes according to what you do with it. Many other studies have also implied an association between hippocampal size and navigational ability – for instance, people with Alzheimer’s, who have lost neurons in this brain structure, tend to experience problems finding their way around. For some time, then, an obvious, though tentative, inference has been that better navigators have bigger hippcampi, with London taxi drivers (and their mastery of “the knowledge” of the city’s convoluted streets) and people with Alzheimer’s representing opposite extremes of the spectrum. However, a new study, released as a preprint at bioRxiv, raises questions about how far we can safely generalise from the taxi driver and Alzheimer’s-based research.
Steven Weisberg and his colleagues tested young adults’ navigation skills and assessed the size of their hippocampi and found the two were not significantly correlated. “The hippocampus plays a crucial role in spatial navigation in humans, but the volume of the hippocampus may not be a biological marker for navigation ability among typical populations,” the researchers concluded.