London taxi drivers and bus drivers: A structural MRI and neuropsychological analysis

Abstract

Licensed London taxi drivers show that humans have a remarkable capacity to acquire and use knowledge of a large complex city to navigate within it. Gray matter volume differences in the hippocampus relative to controls have been reported to accompany this expertise. While these gray matter differences could result from using and updating spatial representations, they might instead be influenced by factors such as self-motion, driving experience, and stress. We examined the contribution of these factors by comparing London taxi drivers with London bus drivers, who were matched for driving experience and levels of stress, but differed in that they follow a constrained set of routes. We found that compared with bus drivers, taxi drivers had greater gray matter volume in mid-posterior hippocampi and less volume in anterior hippocampi. Furthermore, years of navigation experience correlated with hippocampal gray matter volume only in taxi drivers, with right posterior gray matter volume increasing and anterior volume decreasing with more navigation experience. This suggests that spatial knowledge, and not stress, driving, or self-motion, is associated with the pattern of hippocampal gray matter volume in taxi drivers. We then tested for functional differences between the groups and found that the ability to acquire new visuo-spatial information was worse in taxi drivers than in bus drivers. We speculate that a complex spatial representation, which facilitates expert navigation and is associated with greater posterior hippocampal gray matter volume, might come at a cost to new spatial memories and gray matter volume in the anterior hippocampus.

The neuroanatomy of bilingualism: how to turn a hazy view into the full picture

“…However, taken together, the results of these studies demonstrating how brain structure changes due to bilingual experience are 9 heterogeneous and sometimes conflicting: while some studies have found a variety of neural regions that differ between bilinguals and monolinguals with a certain degree of consistency, others have failed to show any bilingual-specific effect or have reported localized differences in inconsistent brain areas. In contrast to the findings from studies exploring forms of expertise not related to language (Maguire et al, 2000;Maguire, Woollett & Spiers, 2006;Gaser & Schlaug, 2003), the hazy picture obtained from neuroimaging studies of bilingual-specific effects demonstrates that it is unclear where precisely the structural neural differences between monolingual and bilingual samples lie, and what the main factors leading to these structural differences are.…”

Invited Address: “The Times They Are A-Changin’” Gene Expression, Neuroplasticity, and Developmental Research

“…Such work challenges the view that intelligence is a set of innate, immutable abilities. Other studies have reported the growth of areas in the brain associated with context and space among taxicab drivers (Maguire et al 2006) and of areas associated with finger movements in virtuoso violinists (Elbert et al 1995). Indeed, simply repeatedly imagining oneself playing a simple five-note sequence on the piano has been shown to increase the space in the motor cortex devoted to the fingers (Pascual-Leone et al 2005).…”

The construction system of the brain

“…Further empirical evidence hinting at a two-process function of the hippocampus comes from structural MRI studies of expert navigators (London taxi drivers) who show increased grey matter volume in posterior hippocampus seemingly at the expense of reduced grey matter volume in anterior hippocampus (Maguire et al 2006b). Moreover, their increased spatial knowledge appears to come at a cost to the acquisition of new visual associative information (Maguire et al 2006b;Woollett & Maguire 2009).…”