Thank you for your answer. We will check the pial and white surfaces, but how to check the accuracy of the cortical parcellation beyond that? We don't find any suggestion on Freesurfer's troubleshooting page how to realize or correct such an error, where the pial and white surfaces are good but the cortical parcellation is not accurate. Manual intervention is only suggested for the aseg segmentations. Could you please suggest some more details about how to check/correct the possible errors in cases where both pial and white surfaces are accurate?