Neuroscience in Public View

References

Cite

Share

Abstract

The role of the hippocampus in spatial memory is, of course, well established, and a number of important studies have implicated the hippocampus in navigation in humans. Recent studies indicate that in some lower species, there is an increase in hippocampal volume during seasons when spatial memory and navigation are utilized the most. Building on those observations, Maguire et al. (1), in a study that was widely quoted in the lay press, asked whether morphological changes can be detected in the healthy adult human brain in association with extensive experience at spatial navigation. Using voxel-based morphometry to analyze structural MRIs, these investigators studied the brains of licensed London taxi drivers who had undergone an extensive period of training in which they had learned how to navigate efficiently between virtually all of the streets within London. Notably, the posterior hippocampi of taxi drivers were significantly larger than those of control subjects, whereas more anterior hippocampal areas were larger in the controls. These results add to the body of evidence indicating that the hippocampus is preferentially involved in spatial navigation. Maguire et al. also asked whether there was a correlation between the amount of time spent as a taxi driver and hippocampal volume and found a positive correlation for the posterior hippocampus and a negative correlation for the anterior hippocampus. The observation of a correlation between the magnitude of the volume increase and the length of time spent as a taxi driver suggests that changes in hippocampal structure are not a result of inborn differences between brain structure in different individuals but, on the contrary, are acquired as a result of training and/or experience. These elegant results, which are also discussed in Perspectives on Neuroscience and Behavior in this issue, provide evidence for structural plasticity within the human brain as a function of increasing exposure to environmental stimuli. As pointed out by the authors, these observations may have important implications for rehabilitation following various insults to the brain.