Mnemonic brain state engagement is diminished in healthy aging

Area of Science:

• Cognitive Neuroscience
• Neuroscience of Aging

Background:

• Episodic memory declines with age, while semantic memory remains intact.
• Older adults struggle to inhibit prior knowledge retrieval, possibly impacting new memory formation.
• Mnemonic brain states, encoding and retrieval, are crucial for memory function and may be differentially engaged with age.

Purpose of the Study:

• To investigate age-related differences in mnemonic brain state engagement.
• To test the hypothesis that older adults are biased toward a retrieval state.
• To understand how differential engagement in encoding and retrieval states affects episodic memory in aging.

Main Methods:

• Scalp electroencephalography (EEG) was used to record brain activity in young, middle-aged, and older adults.
• A memory task required participants to selectively encode new stimuli or retrieve previously learned information.
• Multivariate pattern analysis (MVPA) of spectral activity decoded engagement in retrieval versus encoding states.

Main Results:

• All age groups could selectively engage encoding or retrieval states based on instructions.
• Mnemonic brain states were successfully decoded for all participants.
• Older adults exhibited diminished mnemonic brain state engagement compared to middle-aged adults.

Conclusions:

• Age-related episodic memory decline may stem from differential engagement in mnemonic brain states.
• Executive control deficits and a bias toward retrieval contribute to reduced mnemonic state engagement in older adults.
• Findings suggest that altered brain state dynamics underlie memory changes observed in aging.