Navigation expertise and the human hippocampus: a structural brain imaging analysis

ABSTRACT: Grey matter volume in the posterior hippocampus of Lon-don taxi drivers is greater than in age-matched controls, and the size of this increase correlates positively with time spent taxi driving (E.A. Magu-ire et al., 2000. Proc Natl Acad Sci U S A 97: 4398–4403). This change suggests that increased posterior hippocampal grey matter volume is acquired in response to increased taxi driving experience, perhaps reflect-ing their detailed representation of the city. However, an alternate hy-pothesis is that the difference in hippocampal volume is instead associated with innate navigational expertise, leading to an increased likelihood of becoming a taxi driver. To investigate this possibility, we used structural brain imaging and voxel-based morphometry (VBM) to examine a group of subjects who were not taxi drivers. Despite this group showing a wide range of navigational expertise, there was no association between exper-tise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain). This failure to find an association between hippocampal volume and navigational expertise thus suggests that structural differences in the human hippocampus reflect the detail and/or duration of use of the spatial representation acquired, and not innate navigational expertise per se. Hippocampus 2003;13:208–217. © 2003 Wiley-Liss, Inc. KEY WORDS: hippocampal grey matter; VBM; virtual reality; wayfind-in