Recollection-related fMRI effects in entorhinal cortex predict longitudinal memory change in healthy older adults

The present study examines whether structural and functional variability in medial temporal lobe (MTL) neocortical regions correlate with individual differences in episodic memory and longitudinal memory change in cognitively healthy older adults. To address this question, older adults were administered a battery of neuropsychological tests on three occasions: the second occasion one month after the first test session, and a third session three years later. Structural and functional MRI data were acquired between the first two sessions and included an in-scanner associative recognition procedure enabling estimation of MTL encoding and recollection fMRI BOLD effects. Encoding effects in parahippocampal cortex correlated with associative recognition performance and baseline cognitive ability. Recollection effects in entorhinal cortex correlated with associative recognition performance and predicted memory change over the three-year follow-up interval, an association that remained after controlling for chronological age and entorhinal cortical volume. These findings suggest that entorhinal recollection effects may be indicative of the future functional integrity of the region and, hence, its capacity to support future memory performance.