Knowing how confidently we know

Here is a fascinating piece of work from Miyamoto et al. showing that parallel stream of information in the brain regulate the confidence that a memory is correct, apart from the memory itself. From the journal's description of the work:

Self-monitoring and evaluation of our own memory is a mental process called metamemory. For metamemory, we need access to information about the strength of our own memory traces. The brain structures and neural mechanisms involved in metamemory are completely unknown. Miyamoto et al. devised a test paradigm for metamemory in macaques, in which the monkeys judged their own confidence in remembering past experiences. The authors combined this approach with functional brain imaging to reveal the neural substrates of metamemory for retrospection. A specific region in the prefrontal brain was essential for meta mnemonic decision-making. Inactivation of this region caused selective impairment of metamemory, but not of memory itself.

and, the abstract from Miyamoto et al.:

We know how confidently we know: Metacognitive self-monitoring of memory states, so-called “metamemory,” enables strategic and efficient information collection based on past experiences. However, it is unknown how metamemory is implemented in the brain. We explored causal neural mechanism of metamemory in macaque monkeys performing metacognitive confidence judgments on memory. By whole-brain searches via functional magnetic resonance imaging, we discovered a neural correlate of metamemory for temporally remote events in prefrontal area 9 (or 9/46d), along with that for recent events within area 6. Reversible inactivation of each of these identified loci induced doubly dissociated selective impairments in metacognitive judgment performance on remote or recent memory, without impairing recognition performance itself. The findings reveal that parallel metamemory streams supervise recognition networks for remote and recent memory, without contributing to recognition itself.