231 — Interbrain cortical synchronization encodes multiple aspects of social interactions in monkey pairs

One monkey sits in an electric wheelchair. Another monkey watches from a fixed vantage point. The monkey is driven (by a random trajectory) to a reward target. When the monkey arrives at the target, both observer and passenger monkeys receive a reward.

Then the monkeys switch places.

The goal of this research was to determine how monkeys encode information like position of both themselves and their peers in space, as well as how monkeys encode distance and displacements to food rewards.

Recording transcranially from both monkeys, the researchers discovered that the signals from the primary motor cortex (M1) of passenger and observer monkey synchronized (“interbrain cortical synchronization”) and carried very similar signals at “focal points” of the trajectory, including times at which the chair either stopped, turned, or changed direction.

This is the canonical use-case for “mirror neurons,” or families of neurons that appear to represent similar information across two individuals’ brains. I’m usually very hesitant to talk about mirror neurons because they’re a target for pseudoscientific analogies…but in this case, I think it’s fair to use the term to indicate that this interbrain synchrony is most likely a product of monkeys being able to project their own understanding of situation and movement into their hypothesized representation of a peer.