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Dear JL Hsu The answer should be no. When normalisation is performed with "preserve total" the structural images are actually modulated with the determinant of the deformation field. Due to this the intensity values of the images are changed and the subsequent segmentation algorithm will try to undo this modulation when creating GM, WM and CSF probability maps. The proper way should be running the CG scripts with "preserve concentration" and finally analysing either the regular compartment outputs or modulated compartment outputs if the interest is respectively in differences in tissue concentration or tissue volume. Kind regards, Dr. Dennis van 't Ent Dept. Biological Psychology Vrije Universiteit, Amsterdam, The Netherlands -----Oorspronkelijk bericht----- Van: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] Namens JL Hsu Verzonden: woensdag 10 augustus 2005 10:45 Aan: [log in to unmask] Onderwerp: [SPM] VBM and normalisation question ? Dear SPM experts, I have a question about VBM study when I use the Christian Gaser's script to do the study. When I use the cg_create_template and cg_vbm_optimized script, should I change the spm normalisation default from "preserve concentration" to "preserve total" ? thanks replay