I am not super experienced in MRI/fMRI analysis, and I started to use SPM and/or FreeSurfer for statistical mapping.
I see that most of the work done on the data is to fit a glm and then discuss contrasts and do some inference based of t-scores for instance.
To be able to interpret correctly these analyses (in terms of probabilities and null hypothesis rejection), we must check that the residuals satisfies homoscedasticity and, of course, normality. For those criterion we can for instance use the Breusch–Pagan test and Shapiro-Wilk test (respectively), but I haven’t seen any tools (in SPM or FS) to create those maps.
Does anyone knows if these tests (or any other similar test, e.g. Smirnov-Kolmogorov test for normality or even Q-Q plots) are implemented in some software?