Figure 3.

Entorhinal–hippocampal functional connectivity (FC) is related to object mnemonic discrimination and Aβ status. FC strength (Fisher z-transformed semipartial correlation values) was calculated between each region pair corresponding to canonical anatomical connections within the entorhinal–hippocampal circuit. A, FC strength was compared between high (MDTO+, light red) and low (MDTO–, dark red) performers on the MDTO. Low performers had significantly increased FC between alEC and DG/CA3H compared with high performers, but no other differences across the circuit. B, FC strength was compared between high (MDTS+, light blue) and low (MDTS–, dark blue) performers on the MDTS. There were no significant differences in FC strength; however, there was a trend-level association for decreased pmEC–DG/CA3H FC in the low performers compared with high performers. C, FC strength was compared between Aβ– (light green) and Aβ+ (dark green) participants. Aβ+ participants had significantly increased FC between alEC and DG/CA3H compared with Aβ– participants, which is consistent with the pattern found in the MDTO– group. Aβ+ participants also had decreased FC between CA1H and SubH, and a trend-level association for decreased FC between DG/CA3H and CA1H compared Aβ– participants. D, Control analyses tested whether performance on a traditional episodic memory measure, the RAVLT delayed recall, was associated with changes in entorhinal–hippocampal FC. There was no difference in FC between high (RAVLT+, light purple) and low (RAVLT–, dark purple) performers, indicating specific effects for mnemonic discrimination. Error bars represent the SEM. **p < 0.01, *p < 0.05, +p < 0.10.