Technical notes

This topic describes technical details of transforming SPM cluster data to Talairach space and assumes knowledge of the MATLAB volume visualization techniques, as well as SPM clusters data representation.

The following steps are performed to transform cluster data into Talairach space:

1. Calculating bounding box of the cluster in the MNI space and constructing MATLAB volume data in the MNI space (MATLAB meshgrid function used to construct 3D grid coordinates, voxel size as in SPM is used).
2. Applying non-linear transformations, as described at CBU Imaging web site, to every point in 3D grid to get non rectangular grid coordinates in Talairach space.
3. On the basis of the non rectangular grid in Talairach space calculate bounding box of the cluster in the Talairach space.
4. Calculating MATLAB volume data in the Talairach space (MATLAB meshgrid function used to construct 3D grid coordinates, voxel size as set by Option Voxel Size menu command is used). For calculating data values for points of rectangular 3D grid in Talairach space MATLAB function interp3 with linear interpolation is used (data on rectangular grid are interpolated on the basis of data on non rectangular grid from step 3).