I have a question on what kind of mask images should be set when performing the whole brain searchlight analysis.
Following “decoding_template.m”, I’m using a “mask.nii” as a mask image for each participant (cfg.files.mask), which was generated when performing SPM 1st-level specify. I’ve performed the whole brain searchlight RSA using those mask images. But in some results, I observed “leaky” signals (i.e., signals observed outside the cortex) in the group-level statistic as shown in the attached picture. I guess that this would be due to the results of my preprocessing (I’m wondering to try segmentation or change some normalization parameters. If there are any recommended methods for better segmentation, please let me know). Or, I’m also wondering whether I should use different images instead of mask.nii as ROI masks. I would be very happy if I could get some tips on this topic.
TDT is really helpful for my research. Thanks a lot!