VBM findings. (a Left) Sagittal section of an MRI scan with the hippocampus indicated by the red box. (a Right) Coronal section through the MRI scan, again with the hippocampi indicated. (b) The group results are shown superimposed onto the scan of an individual subject selected at random. The bar to the right indicates the Z score level. Increased gray matter volume in the posterior of the left and right hippocampi (LH and RH, respectively) of taxi drivers relative to those of controls, shown in the top of the figure in sagittal section. Underneath, the areas of gray matter difference are shown in coronal sections at three different coordinates in the y axis to illustrate the extent of the difference down the long axis of the hippocampus. (c) Increased gray matter volume in the anterior of the left and right hippocampi of controls relative to those of taxi drivers, shown in sagittal section. Note that, although the Talairach and Tournoux (11) coordinate system was used to describe the locations of VBM differences in stereotactic space, the images were normalized with respect to a template based on a large number of brains scanned in the same scanner used to collect the current data (see Methods). Thus, the coordinates given refer to our brain template and only approximately to the Talairach and Tournoux template.

Correlation of volume change with time as a taxi driver. (a Left) Sagittal section. (a Right) Coronal section. The VBM group results are shown superimposed onto the scan of an individual subject selected at random. The bar to the right indicates the Z score level. The volume of gray matter in the right hippocampus was found to correlate significantly with the amount of time spent learning to be and practicing as a licensed London taxi driver, positively in the right posterior hippocampus (b) and negatively in the anterior hippocampus (c).

Volumetric analysis findings. The orientation of the slices measured in the volumetric analysis with respect to the hippocampus is shown (Top Right Inset). A, anterior; B, body; P, posterior. (Upper) The mean of the cross-sectional area measurements (uncorrected for ICV) for the three regions of the left hippocampus (LH). (Lower) The means for the right hippocampus (RH). Taxi drivers had a significantly greater volume relative to controls in the posterior hippocampus, and controls showed greater hippocampal volume in the anterior. There was no difference between the two groups in the hippocampus body. *, P < 0.05.