Age-Related Differences in Short Term Spatial Memory in Rhesus Macaques.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Primatology

Background:

• Previous research identified working memory deficits in very old macaques compared to younger ones.
• Middle-aged macaques (14-19 years) have not been thoroughly assessed for working memory performance.
• Understanding age-related cognitive changes is crucial for primate welfare and research.

Purpose of the Study:

• To develop a high-throughput adaptation of the delayed response task for assessing spatial working memory in middle-aged macaques.
• To compare working memory performance across a wide age range of rhesus macaques (7-27 years).
• To identify age-dependent cognitive differences, including learning and perseveration.

Main Methods:

• A manual 3-choice delayed response task was administered to male and female rhesus macaques.
• Task acquisition used a short 1-second delay, followed by variable delays (5-60s) for memory probing.
• A novel method was developed to quantify response distribution and assess perseverative responding.

Main Results:

• Retrieval accuracy significantly decreased with both increasing delay length and increasing age.
• Age-dependent differences were observed in memory, learning, and perseveration.
• The results suggest a decline in cognitive flexibility in older macaques contributes to memory deficits.

Conclusions:

• The refined delayed response task provides a sensitive measure of age-related spatial working memory decline.
• Cognitive flexibility appears to decrease in late adulthood, impacting memory performance.
• This task refinement offers a novel approach to quantifying errors in age-sensitive spatial memory tasks.