Age-related individual variability in memory performance is associated with amygdala-hippocampal circuit function and emotional pattern separation

• Published in: Neurobiology of aging Vol. 49; pp. 9 - 19
• Main Authors: Leal, Stephanie L., Noche, Jessica A., Murray, Elizabeth A., Yassa, Michael A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2017
• Subjects: Aged; Aged, 80 and over; Aging; Aging - pathology; Aging - physiology; Aging - psychology; Amygdala; Amygdala - diagnostic imaging; Amygdala - physiology; Emotion; Emotions - physiology; Female; Hippocampus; Hippocampus - diagnostic imaging; Hippocampus - physiology; Humans; Internal Medicine; Lateral entorhinal cortex; Learning - physiology; Magnetic Resonance Imaging; Male; Memory; Memory - physiology; Middle Aged; Nerve Net - diagnostic imaging; Nerve Net - physiology; Neurology; Psychomotor Performance - physiology; Aging; Emotion; Lateral entorhinal cortex; Amygdala; Memory; Hippocampus; lateral entorhinal cortex; amygdala; memory; emotion; aging; hippocampus
• ISSN: 0197-4580; 1558-1497
• DOI: 10.1016/j.neurobiolaging.2016.08.018

While aging is generally associated with episodic memory decline, not all older adults exhibit memory loss. Furthermore, emotional memories are not subject to the same extent of forgetting and appear preserved in aging. We conducted high-resolution fMRI during a task involving pattern separation of emotional information in older adults with and without age-related memory impairment (characterized by performance on a word-list learning task: low performers: LP vs. high performers: HP). We found signals consistent with emotional pattern separation in hippocampal dentate (DG)/CA3 in HP but not in LP individuals, suggesting a deficit in emotional pattern separation. During false recognition, we found increased DG/CA3 activity in LP individuals, suggesting that hyperactivity may be associated with overgeneralization. We additionally observed a selective deficit in basolateral amygdala—lateral entorhinal cortex—DG/CA3 functional connectivity in LP individuals during pattern separation of negative information. During negative false recognition, LP individuals showed increased medial temporal lobe functional connectivity, consistent with overgeneralization. Overall, these results suggest a novel mechanistic account of individual differences in emotional memory alterations exhibited in aging.