FIGURE 1.

The criteria to determine the optima number of clusters. The average silhouette values and the changes of gradient were used to select the number of clusters. (a) The average silhouette values identified the optimal three‐way parcellation for bilateral hippocampus which show stable changes of the maximum average silhouette across more than 300 steps. (b) The gradient value of average silhouette values across all the steps were depicted and no blunt change of gradient was found when hippocampus were parcellated into three subregions (K = 3). Thus, the optimal three‐way parcellation of hippocampus was finally used in this study