Cognitive Strategy Accounts for Failure on a Relational Memory Task in Non-Human Primates

Area of Science:

• Cognitive Neuroscience
• Comparative Psychology
• Neurobiology of Aging

Background:

• Relational memory, crucial for associating distinct elements, depends on the hippocampus and declines with age in humans.
• The Transverse Patterning (TP) task assesses relational memory through hierarchical, circular relationships, similar to rock-paper-scissors.
• Human TP performance is impaired by hippocampal damage and aging, but non-human primate results are inconsistent, suggesting differing cognitive strategies.

Purpose of the Study:

• To investigate whether non-human primates use elemental (stimulus-response) rather than configural (hippocampal-dependent relational) strategies on the TP task.
• To explore age-related cognitive differences in relational memory in common marmosets.
• To clarify species-specific cognitive strategies in memory research.

Main Methods:

• Young and aged common marmosets were trained on the TP task and control tasks isolating elemental versus configural learning.
• Performance on tasks requiring integration of multiple relationships versus simple associations was compared.
• Age-related differences in task performance were assessed.

Main Results:

• Marmosets successfully learned simple stimulus-reward associations but failed tasks requiring integration of all relationships (TP task).
• All marmosets readily learned control tasks solvable by elemental strategies.
• No age-related impairments were observed in marmosets on either TP or control tasks.

Conclusions:

• Common marmosets employ a habit-based, elemental learning strategy ill-suited for relational demands, unlike humans.
• Species differences in cognitive strategy use, not just hippocampal function, explain divergent findings in cross-species memory studies.
• The findings underscore the need to validate neural systems engaged by tasks across species in translational memory research.