Macaques, like humans, know how well they can recall memories

Evaluating one's own memory requires access to information about the strength of memory traces, though the brain structures and neural mechanisms involved in this effort -- and whether they are distinct from normal memory recall -- remain unknown.

Here, to shed light in this space, Kentaro Miyamoto and colleagues devised a metamemory test in which macaques judged their own confidence in remembering past experiences; the animals opted for higher bets on the outcome of a memory recall test when they were surer their memory judgments were correct.

Using this setup, as well as whole-brain searches by functional neuroimaging, the researchers identified a specific region in the prefrontal brain essential for metamemory decision making. Its inactivation caused selective impairment of metamemory, but not of memory itself.

The results pave the way to further study of the neuronal underpinnings of metacognition using an animal model, where metamemory has previously been difficult to evaluate.