Effects of Aging on Successful Object Encoding: Enhanced Semantic Representations Compensate for Impaired Visual...

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Aging Research

Background:

• Episodic memory and visual processing decline with age, while semantic knowledge remains relatively preserved.
• Older adults' preserved semantic knowledge may support episodic memory function.
• Understanding age-related changes in neural representations is crucial for explaining memory differences.

Purpose of the Study:

• To investigate how visual and semantic representations during encoding predict memory vividness in young and older adults.
• To examine age-related differences in the specificity of neural representations for visual and semantic features.
• To explore the compensatory role of semantic knowledge in supporting memory vividness in aging.

Main Methods:

• Functional magnetic resonance imaging (fMRI) and representational similarity analyses (RSAs) were employed.
• Deep convolutional neural network and normative concept feature data modeled neural activity patterns.
• Participants encoded object images and later recalled them, rating memory vividness.

Main Results:

• Older adults exhibited reduced specificity of visual feature representations (dedifferentiation) but enhanced specificity of semantic feature representations (hyperdifferentiation).
• Visual representations in early visual cortex predicted memory vividness in both age groups.
• Semantic representations in lingual and fusiform gyri uniquely supported memory vividness in older adults.
• Higher semantic and lower visual representation specificity correlated with greater memory vividness in older adults.

Conclusions:

• Memory vividness in aging relies more on semantic representations, particularly in anterior brain regions.
• Enhanced semantic processing may compensate for age-related dedifferentiation of visual information in posterior regions.
• Findings suggest a shift in memory encoding strategies with age, leveraging preserved semantic knowledge.