The only significant latent variable to emerge corresponded to a contrast of pHPC and aHPC bilaterally, with this divergence especially apparent in the right hemisphere (n = 13; singular value = 8.9, p < 0.05) (Figure 3A). A nonrotated version of this analysis confirmed that a contrast of pHPC and aHPC connectivity was significant at the whole-brain level. The underlying spatial pattern involved preferential correlation between Epigenetics Compound Library datasheet pHPC and bilateral dorsolateral prefrontal cortex, left anterior cingulate cortex, bilateral posterior

cingulate cortex and retrosplenial cortex, left precuneus, bilateral thalamus (including anterior and dorsomedial nuclei), bilateral inferior parietal lobe,

and bilateral occipital gyrus regions (Figures 3B–3E; Table S3). aHPC correlated preferentially with the lateral temporal cortex in both hemispheres, extending to the temporal poles bilaterally (Figures 3B–3E). Similar findings have been reported elsewhere (Kahn et al., 2008), but SB431542 ic50 the current results extend prior evidence by formally demonstrating the stability of the overall pattern. Interestingly, the above pHPC- and aHPC-correlated regions are, respectively, the cortical connections of the polysynaptic intrahippocampal pathway (which connects with frontal and parietal cortices via the fornix) and the direct intrahippocampal pathway (which projects to the anterior temporal lobe via the uncinate fasciculus; Duvernoy, 2005; Figure 3F). Connections of the polysynaptic pathway are believed to support

RM by mediating perceptual (precuneus), attentional (inferior parietal), and strategic (lateral frontal) contributions to it (Spaniol et al., 2009). Integrity of the fornix, which connects the polysynaptic pathway to cortex, is also important for RM (Tsivilis et al., 2008 and Gilboa et al., 2006). In contrast, anterior temporal connections of the direct pathway are associated with the processing of semantic information and social and emotional cues (Rogers et al., 2006 and Olson through et al., 2007). Because pHPC linked preferentially with polysynaptic pathway connections, a neural context interpretation is consistent with our finding that larger pHPC volume ratios predict better RM. Hippocampal covariance effects during postencoding rest that are linked to memory success have been interpreted as evidence of hippocampal consolidation (Tambini et al., 2010 and Ben-Yakov and Dudai, 2011). Along these lines, and because pHPC is linked preferentially to regions associated with RM, we explored whether greater pHPC covariance with its functionally connected network during postencoding rest could explain the relationship between pHPC volume ratios and RM.