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> does spm suppose (for inter-subject data averaging and comparison across > tasks, i.e. normalization) that images were acquired in the bi-commisural > plane ? If the data were not acquired in the bi-commisural plane, are there > possibilities in spm to "reangulate" the images into the ac-pc line ? The ORIGIN field in the header should contain the co-ordinates of a voxel (beginning with 1,1,1) that is somewhere near to the Anterior Commisure. Data does not need to be acquired in transverse sections exactly parallel to the AC-PC plane. However, if the orientation of the images is far from the orientation of the template images, then you may need to use the Defaults button to (Spatial Normalization options) to tell the Spatial normalization and Co-registration routines a bit more about the orientation of the images. By default, the estimates look something like: [0 0 0 0 0 0 -1 1 1 0 0 0] or [0 0 0 0 0 0 1 1 1 0 0 0]. The first three parameters represent translations in the x, y and z directions (in millimeters). The second three are rotations (in radians) around the x, y and z axes (i.e., pitch, roll and yaw). See spm_matrix.m and spm_imatrix.m for more information. Good luck, -John %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%