Where is ELSA? The early to late shift in aging

Area of Science:

• Neuroscience
• Cognitive Aging
• Neuroimaging

Background:

• Cognitive and neural aging research indicates a shift from early- to late-onset cognitive control strategies.
• This shift is associated with prolonged prefrontal cortex (PFC) activity, but its occurrence in other brain regions remains unclear.
• The variability of this age-related functional shift across different cognitive processes needs further investigation.

Purpose of the Study:

• To investigate whether an early-to-late shift in aging (ELSA) is observable in the medial temporal lobes (MTL).
• To examine the temporal dynamics of MTL activity during a protracted context memory task.
• To explore the functional connectivity between MTL and PFC during different phases of memory retrieval.

Main Methods:

• Utilized a protracted context memory task with distinct retrieval preparation and retrieval completion phases.
• Employed neuroimaging techniques to measure brain activity and functional connectivity in young and older adults.
• Analyzed MTL and PFC activity patterns and their inter-regional connectivity during the memory task.

Main Results:

• Older adults exhibited reduced MTL activity during early retrieval preparation and increased MTL activity during late retrieval completion.
• Functional connectivity between MTL and PFC was higher in young adults during retrieval preparation.
• Conversely, older adults showed higher MTL-PFC connectivity during retrieval completion, indicating an interactive relationship.

Conclusions:

• The findings suggest that the early-to-late shift in aging (ELSA) extends to the medial temporal lobes (MTL), not just the prefrontal cortex (PFC).
• Aging leads to temporally lagged neural activity in brain regions like the MTL, even those not traditionally considered central to cognitive control.
• The interactive relationship between MTL and PFC functional connectivity highlights age-related changes in memory retrieval processes.