Effects of aging on transient and sustained successful memory encoding activity

Area of Science:

• Neuroscience
• Cognitive Aging
• Neuroimaging

Background:

• Event-related fMRI studies examine age-related memory encoding changes using difference in memory (Dm).
• Distinguishing between transient and sustained neural activity provides deeper insights into encoding processes.

Purpose of the Study:

• To investigate age-related differences in transient and sustained neural activity during memory encoding.
• To explore the role of the hippocampus and prefrontal cortex (PFC) in age-related memory changes.

Main Methods:

• Utilized hybrid blocked/event-related fMRI analyses to measure difference in memory (Dm).
• Dm was assessed parametrically based on subsequent memory and confidence ratings.
• Transient Dm was measured per trial; sustained Dm was measured in blocks of eight trials.

Main Results:

• Transient Dm analyses revealed age-related reductions in the left hippocampus and increases in the left prefrontal cortex (PFC).
• Sustained Dm analyses showed age-related reductions in the right PFC, with no regions showing increased activity in older adults.
• Older adults exhibited less spontaneous hippocampal activity but greater PFC-mediated semantic processes during encoding.

Conclusions:

• Age-related changes in memory encoding involve both transient and sustained neural activity.
• Reduced hippocampal activity suggests less spontaneous encoding in older adults, while increased PFC activity indicates greater reliance on semantic processes.
• Deficits in sustained attention may contribute to age-related declines in sustained neural activity during encoding.