Layer V perirhinal cortical ensemble activity during object exploration: a comparison between young and aged rats.

Area of Science:

• Neuroscience
• Cognitive Aging
• Memory Research

Background:

• Object recognition memory is crucial for daily function.
• The perirhinal cortex (PRC) is vital for object recognition.
• Cognitive functions, including memory, decline with normal aging.

Purpose of the Study:

• To investigate if age-related deficits in object recognition memory are linked to altered neural activity in the PRC.
• To examine the activity of PRC neurons during object exploration in young and aged rats.

Main Methods:

• Used cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH) and confocal microscopy.
• Monitored activity-induced Arc RNA in layer V of the PRC in young and aged rats.
• Assessed neural activity during two object exploration epochs in familiar (AA) and changed (AB) environments.

Main Results:

• Both young and aged rats demonstrated successful object recognition, exploring less in the second session.
• In a changed environment (AB), more neurons were active in the second exploration epoch, suggesting neural adaptation.
• Aged rats exhibited significantly lower proportions of Arc-positive PRC neurons compared to young rats in both AA and AB conditions.

Conclusions:

• Age-associated functional alterations in the PRC contribute to declines in stimulus recognition.
• Reduced neural activity in the PRC may underlie age-related object recognition memory deficits.
• Neural ensemble recruitment in the PRC might signal familiar stimuli in novel contexts.