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FIG 5. Line-drawings corresponding to MR images in Figure 4 summarize the anatomic landmarks used to draw the outlines of the PCA. Only the images displaying critical landmarks are shown. In section #1 (Fig 4A), the appearance of the limen insulae (LI) marks the reference level for outlining the PCA. At this level, the PCA extends 30% of the distance between the endorhinal sulcus (es) to the most convex point of the medial temporal cortex (asterisk). Its thickness is reaches 25% that of the adjacent perirhinal cortex (PRC). In section #2 (Fig 4B), the PCA occupies 50% of the distance of the endorhinal sulcus-medial temporal lobe convexity (arrow). Its thickness is 25% of that of the adjacent PRC. In section #2 (Fig 4C), the PCA extends down as far as the continuation of the limit of the white matter at its crossing with the pial surface (alternatively, if it were absent, the limit is given by the visualization of the sulcus semiannularis). This distance represents up to 80% of the distance of the es-medial temporal lobe convexity. The PCA borders ventrally the most medial aspect of the entorhinal cortex (EO subfield) (49). Its thickness is 25% that of the adjacent PRC. Section #4 (Fig 4D) is at the level of the rostralmost portion of the amygdala. At this level, the PCA extends from the endorhinal sulcus down to the sulcus semiannularis (ssa), or in its absence, as in the previous level. Its thickness encompasses the entire cortical gray matter. In section #6 (Fig 4F), the amygdala is larger. The PCA occupies the entire medial temporal cortex down from the endorhinal sulcus to the sulcus semiannularis. Its thickness encompasses the entire cortical gray matter. In sections 7–9 (Fig 4G–I), the rostral hippocampus appears. The PCA is defined as in level #6. In section #11, the opening of the hippocampal fissure (hf) marks the last image to be quantified. HC indicates hippocampus; cs, colateral sulcus; Sub, subiculum. Scale bar equals 10 mm (all panels).
