Summary: The study shows that the posterior inferior parietal lobe plays a crucial role in integrating information from different sources during decision-making.
Three RIKEN neuroscientists have found a brain region in macaques that is responsible for integrating information from different sources in decision-making.
This finding, published in cell reportswill help inform research on psychiatric disorders that impair introspection.
Sometimes we need to base our decisions on both our memories and the current facts before us. An example is trying to decipher a hastily scrawled note while trying to remember what we wrote about. To reach a decision, our brain assigns confidence levels to the two sources of information and then combines them.
Known as metacognition, this ability to self-evaluate thoughts and memories underpins many behaviors. But it wasn’t clear where the brain integrates this information when making decisions.
Now, Kentaro Miyamoto, Rieko Setsuie, and Yasushi Miyashita, all at the RIKEN Center for Brain Science, have shown through experiments in macaque monkeys that a brain region known as the posterior inferior parietal lobe (pIPL) performs this integration.
The monkeys were shown a picture and had to decide whether or not they had seen it before. To assess their confidence in their decision, the monkeys had to bet on it, choosing between high-risk/high-reward or low-risk/low-reward options.
Perhaps unsurprisingly, the monkeys chose the high-risk option more often when they answered the question correctly than when they answered it incorrectly. This indicated that the monkeys employed effective metacognition processes.
Functional magnetic resonance imaging during these experiments showed that the pIPL was active while the monkeys weighed their betting options based on the memory test.
Miyamoto was surprised by this. “The prefrontal cortex is thought to be the key region for monitoring behavior and making rule-based decisions; Some believe that the ‘intelligence of the soul’ resides there,” he explains.
“So I was very surprised that whole-brain mapping indicated that a region in the back of the brain was active during metacognition.”
The pIPL relied on information from three brain regions in the prefrontal cortex that Miyamoto and Miyashita’s team previously found to be involved in determining trust in memories. “The memory system itself is not located in the prefrontal cortex, but the prefrontal cortex is important for reading out trust in memories,” says Miyamoto.
The pIPL then sent a signal to another region, the dorsal anterior cingulate cortex, to implement the betting decision.
Miyamoto intends to explore metacognition processing at the neural level and its connection to psychiatric disorders in which people compulsively behave in ways they don’t want.
About this news from decision making research
Author: press office
Contact: Press Office – RIKEN
Picture: The image is credited to RIKEN
Original research: Open access.
“Transformation of Concept-Specific Decision Confidence into Integrative Introspection in Primates” by Kentaro Miyamoto et al. cell reports
Transforming concept-specific decision-making confidence into integrative introspection in primates
- A time-consuming process of compensating for metacognitive evidence occurs in macaques
- The pIPL encodes the interplay of performance and confidence
- The pIPL integrates trust specific to the concept of experience and novelty
- The pIPL prompts the dorsal anterior cingulate cortex to issue strategic actions
Introspection, based on the integration of uncertain evidence, is crucial to acting on abstract thinking and imagining future scenarios.
However, it is unknown how confidence readings from multiple sources of different concepts are integrated, especially considering the relationships between the concepts. In this study, monkeys made bets based on an estimate of their performance in a previous mnemonic decision.
We found that the longer the reaction times for post-decision bets, the better the impairments caused by frontal interference. This suggests the existence of a time-consuming compensatory metacognitive process.
We found the posterior inferior parietal lobe (pIPL) as its candidate, which did not encode the bets per se (i.e. only high bet or low bet), but became more active when monkeys successfully chose the optimal betting option based on mnemonic decision performance.
Thereafter, the pIPL prompts the dorsal anterior cingulate cortex to bear the chosen betting option. Our results suggest a role for the pIPL in metacognitive concept integration.