Hi all,

I am working on an fMRI study comparing older adults to young adults. We are running our analyses in AFNI and would like to make one atlas from our subject data that could be utilized for preprocessing all participants. This technique was suggested during my lab's attendance of the AFNI Bootcamp at WashU in January.

I have gathered some resources from the workshop (specifically the Alignment and Atlases handout), the website for creating an atlas (https://sscc.nimh.nih.gov/sscc/dglen/Makinganatlas), and have spent some time looking through the AFNI message boards, but I am still unclear on how exactly the atlas should be made and what the input should be.

I currently have two specific questions, and would also appreciate any additional insight into this process you all think we might need!

1. To fairly represent the young and older adults in our sample, how many single subject scans are recommended to create this atlas? Should we use our entire sample, or would you suggest using a subset of our sample?

2. The code for creating an atlas from your website is as follows:

@AfniEnv -set AFNI_SUPP_ATLAS_DIR ~/CustomAtlases/
@Atlasize -space MNI -dset hmat_spm_final.nii \
-lab_file keys.txt 1 0 -lab_file_delim ';' \
-atlas_type G -atlas_name HMAT -atlas_description 'Motor Meta'

The 'keys.txt' file this code references to - what information should be included in this file, and how do we go about getting that information from our single subject scans?

Thank you in advance for any help or insight you all can offer - we really appreciate!

Best,
Samantha