Voxel-based morphometry

Voxel based morphometry (VBM) is a neuroimaging analysis technique that allows investigation of focal differences in brain volume. It can be regarded as a form of so-called statistical parametric mapping. Traditionally, brain volume is measured by drawing regions of interest (ROIs) and calculating the volume enclosed. However, this is time consuming and can only provide measures of large areas. Smaller differences in volume may be overlooked. VBM registers every brain to a template, which gets rid of most of the large differences in brain anatomy among people. Then the brain images are smoothed so that each voxel represents the average of itself and its neighbors. Finally, volume is compared across brains at every voxel.

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One of the first VBM studies and one that came to attention in main stream media was a study on the hippocampus brain structure of London taxi drivers^[1]. The VBM analysis showed the back part of the hippocampus was on average larger in the taxi drivers compared to control subjects while the frontal part was smaller. London taxi drivers need good spatial navigational skills and scientists have usually associated hippocampus with this particular skill.

A key description of the methodology of voxel-based morphometry is Voxel-Based Morphometry—The Methods^[2] — one of the most cited articles in the journal NeuroImage.^[3]

References

^ Eleanor A. Maguire, David G. Gadian, Ingrid S. Johnsrude, Catriona D. Good, John Ashburner, Richard S. J. Frackowiak, and Christopher D. Frith (2000). "Navigation-related structural change in the hippocampi of taxi drivers". Proceedings of the National Academy of Sciences of the United States of America 97 (8): 4398–4403. doi:10.1073/pnas.070039597. Commentary on the original article in the same issue:
- Alejandro Terrazas and Bruce L. McNaughton. "Brain growth and the cognitive map". Proceedings of the National Academy of Sciences of the United States of America 97 (9): 4414–4416.
News story with an interview of the researcher:
- BBC. "Taxi drivers' brains 'grow' on the job", BBC News, 2000-03-14. Retrieved on 2007-03-06.
^ John Ashburner and Karl J. Friston (June 2000). "Voxel-Based Morphometry—The Methods". NeuroImage 11 (6): 805–821. doi:10.1006/nimg.2000.0582.
^ The number of citations is apparent from a search with Google Scholar (2007-12-07) [1].