M&P (Cont): The MRI scanner works by exposing a participant’s brain to a strong magnetic field and radio waves to produce detailed pictures of the brain. Computer software converts the information into a 3D image of the brain and in this study the analysis can calculate the amount of grey matter in the hippocampus.Unlike white matter, Grey matter contains neural cell bodies. To use a computer analogy, the gray matter can be thought of as the actual computers themselves, whereas the white matter represents the network cables connecting the computers together The data were measured using two different techniques – voxel-based morphemetry (VBM) and pixel counting. Voxel-based morphology (VBM) was used in this study to measure the density of grey matter in the brain. VBM provides a three dimensional measurement of volume of an area. Pixel counting was carried out on the scans of the 16 taxi drivers and 16 age-matched controls taken from the 50 control participants. Pixel counting consists of counting the pixels in the images provided by the MRI scans. A pixel is simply a two dimensional measurement of an area. Areas were calculated by taking images of slices of the whole length of the hippocampus.
Results: The first main findings of the research were that the posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and that the anterior hippocampal region was larger in control subjects than in taxi drivers.The second main finding was that hippocampal volume correlated with the amount of time spent as a taxi driver (positively in the right posterior and negatively in the right anterior hippocampus).