Individual differences in associative memory among older adults explained by hippocampal subfield structure and...

Area of Science:

• Neuroscience
• Cognitive Psychology
• Gerontology

Background:

• Older adults often experience episodic memory decline, impacting daily life.
• The medial temporal lobe (MTL) is crucial for memory, and its age-related changes may explain memory differences.
• Understanding these changes is key to addressing memory impairments in aging.

Purpose of the Study:

• To investigate how medial temporal lobe (MTL) structure and function relate to episodic memory performance in older adults.
• To identify specific MTL subfields and functional regions associated with memory variability.
• To determine if combined structural and functional MRI metrics improve prediction of memory performance.

Main Methods:

• Utilized ultra-high-field 7T structural MRI and high-resolution 3T functional MRI (hr-fMRI).
• Assessed medial temporal lobe (MTL) subfield thickness and functional activity during an associative memory task (face-name pair encoding and retrieval).
• Employed regression analyses to link structural and functional metrics to memory performance.

Main Results:

• A combination of entorhinal cortex (ERC) and CA1 apical neuropil layer [CA1-stratum radiatum lacunosum moleculare (SRLM)] thickness and activity in ERC and dentate gyrus (DG)/CA3 regions significantly explained memory performance variability.
• CA1-SRLM thickness showed a positive association with memory performance.
• DG/CA3 retrieval activity demonstrated a negative association with memory performance.

Conclusions:

• Both medial temporal lobe (MTL) structure and function independently and interactively contribute to age-related memory impairments.
• Integrating structural and functional MRI data provides a more comprehensive understanding of memory decline than single-modality approaches.
• These findings offer insights into the neural mechanisms underlying memory differences in aging, complementing existing research.