Defining Brain's Role in the Implication of Social Rewards

Scientists uncover an essential brain circuit involved in gauging the relative worth of individual rewards versus those of others.

Scientists at the National Institute for Physiological Sciences (NIPS) have discovered a significant brain circuit responsible for assessing the value of one's rewards compared to others.

Although you might never have consciously considered it, it’s very likely that when you receive a reward, part of the value that you place on it depends on what other people have received as similar rewards. In a recent study published in Nature Communications, Japanese researchers have identified an important brain circuit for this specific process ().

Brain Circuit Linked to Addiction Remission Identified
Researchers have mapped addiction remission to entire brain circuits using lesion network mapping. The finding points to new targets for addiction treatment.

‘New research reveals a crucial brain circuit that evaluates the subjective value of personal rewards in comparison to others. # Brain Circuit, #Rewards, #Value ’

Although researchers have identified the brain regions that are important for deciding the value of a reward about those of others (a process the authors termed ‘socially subjective reward valuation’), the connections between these regions have never been tested experimentally.

The research team from the National Institute for Physiological Sciences (NIPS) decided to create a temporary disconnect between the medial prefrontal cortex, which is part of the social brain network, and the lateral hypothalamus, which is involved in social reward valuation.

“We used a relatively new technique that is commonly known as DREADD, or ‘designer receptor exclusively activated by designer drug’, in macaque monkeys,” says senior author of the study Masaki Isoda.

Three Brain Circuits Contribute to Parkinson’s Symptoms
Targeting the three brain circuits in the thalamus can offer a new way to reverse motor dysfunction and depression in Parkinson’s patients.

“This method allowed us to temporarily block most of the connections from the brain’s medial prefrontal cortex to the lateral hypothalamus.”

Brain's Social Reward Evaluation Circuit

To test the effects of functionally disconnecting two regions of the monkeys’ brains responsible for socially subjective reward valuation, the researchers used an existing experimental setup.

Two monkeys were sat together and shown pictures on a screen. After seeing each picture, only one of the monkeys (or sometimes neither of the monkeys) received water as a reward.

Visual Areas may Control Your Movement: Reveals New Brain Circuit
Scientists reveal a new visual-motor circuit in the brain, which provides a fresh perspective on the neural mechanisms of movement that occur in the brain.

By varying the probability of reward for each monkey over a series of tests, the researchers were able to see what happened when the monkeys expected a reward for themselves (they made many licking motions with their tongues) versus a reward for the other monkey (they made fewer licking motions).

“Using this test, we were able to see the effects of disconnecting the medial prefrontal cortex from the lateral hypothalamus on the monkeys’ expectations of rewards,” says Isoda.

“We were excited to see that, with this disconnect, the monkeys were much less susceptible to the prospect of others receiving rewards, but that their expectations of a reward did not change, suggesting that this pathway is a key circuit in socially subjective reward valuation only.”

Together with recent research suggesting that the medial prefrontal cortex/lateral hypothalamus circuit is crucial for social rank information in mice, these results indicate that this circuit underlies many important social behaviors.

A better understanding of this pathway will aid in the clinical diagnosis and treatment of injuries or alterations to the medial prefrontal cortex and lateral hypothalamus.

Reference:

Chemogenetic dissection of a prefrontal-hypothalamic circuit for socially subjective reward valuation in macaques - (https://www.nature.com/articles/s41467-023-40143-x)

Source-Eurekalert