the mean across sessions. Across-session variability estimates for all 
400 regions were then averaged across eight participants, and a global 
measure of cortical GMV variability was computed by averaging across 
the 400 regions. This approach was repeated independently for the 
T2 hippocampal scans, wherein we computed across-session variability 
for each parcel of the ASHS parcellation scheme (n = 7 bilateral sub-
fields). However, it is important to note that raw subfield values (that 
is, no manual retouching) were used for Day2Day variability assess-
ments and should be interpreted with caution. Finally, to better com-
pare against our own data, we repeated this approach using our