Download and Install

The first step is to install S²M, SPM25 and CAT in the MATLAB path

1 - Download S²M

2 - Download SPM;

3 - Download CAT

For this version of S²M we recommend the CAT Version 3347 (CAT26.0.rc4)

Then,

4 - Download S²M Database files

This step is optional and is only necessary if you intend to use the provided S²M Standard Normative Database instead of creating your own database from your own control images.

Note that you can download different normative datasets for gray matter (GM) and white matter (WM), with smoothing kernels ranging from 4 × 4 × 4 mm³ to 12 × 12 × 12 mm³ FWHM. The S²M Standard option requires a dataset smoothed with an 8 × 8 × 8 mm³ FWHM kernel. We recommend that new users start by downloading both the GM and WM datasets for this smoothing kernel. The choice of smoothing kernel involves a trade-off between sensitivity and specificity. Lower smoothing levels preserve more spatial detail and may increase sensitivity to small focal alterations. However, they also tend to increase intersubject variability, which can result in more false-positive detections due to natural anatomical variability, noise, and subtle imaging artifacts. Conversely, higher smoothing levels reduce spatial variability and noise but may decrease sensitivity to small or spatially restricted abnormalities.

So far, you should have downloaded the S²M ZIP file, the SPM25 ZIP file, the CAT ZIP file, and, if applicable, a sample of the S²M Standard Database. You should now have a folder containing the following files:

5 - Unzip all files:

6 - Now, add the CAT folder to the spm > toolbox folder:

7 - Now, add the CONTENT of ALL S²M Standard Database folders that you downloaded to the same SSM-1.1 > SSM_Enc_DB folder:

Don't worry if you are asked to replace or ignore some duplicate files.

8 – Finally, add both folders to the MATLAB Path:

And then,

Done, you are now able to run S²M