Dear FreeSurfer Developers,

I was examining the perirhinal and entorhinal annot stats from BA_exvivo_thresh.stats when I noted a significant discrepancy between the left and right hemispheres, particularly obvious on the perirhinal volumes. On a set of 40 scans from normal participants, the means of the perirhinal volumes, in mm3, was 79 on the right hemisphere and 738 on the left hemisphere.

Further visual inspection of the BA annot files, along with a visual examination of the label files, suggests to me that when both the entorhinal and perirhinal cortices encounter the same vertex, the shared vertex would be assigned to the entorhinal cortex in the right hemisphere. This allocation results in an unusually small perirhinal cortex in the right hemisphere for the annotation files, and consequently a much larger right entorhinal cortex. I did not notice this unusual allocation in the left hemisphere. I am rather unclear on why this should be the case.

I am currently using the stable FreeSurfer 7.1 from May 2020 (freesurfer-linux-centos7_x86_64-7.1.0-20200511-813297b). The release notes for version 7.1.1 do not suggest that this specific issue had been addressed, but apologies in advance if it actually had been. I look forward to hearing back from your team. Thank you.

Best regards,

Yi-Leng