Mice and bats’ brains sync up as they interact with their own kind

When animals are together, their brain activity aligns. These simpatico signals, described in bats and mice, bring scientists closer to understanding brains as they normally exist — enmeshed in complex social situations.

Researchers know that neural synchrony emerges in people who are talking, taking a class together and even watching the same movie. But scientists tend to study human brains in highly constrained scenarios, in part because it’s technologically difficult to capture brain activity as people experience rich social interactions (SN: 5/11/19, p. 4). Now two studies published June 20 in Cell offer more details about how synced brains might influence social behavior.

In one study, researchers monitored a pair of Egyptian fruit bats in a dark chamber for more than an hour. Neural implants recorded brain activity as the bats groomed themselves, fought, rested and performed other behaviors.

The brain activity of the two bats was highly coordinated. When one bat’s neural activity oscillated in a fast rhythm, for example, the other bat’s brain was likely to do the same thing. This coordination continued even when the bats weren’t directly interacting with each other, the team found. But when the bats were separated into two chambers in the same room, this correlated activity fell away, suggesting that the bats had to be sharing the same social context for their brains to link up.

A similar result came from a study in mice. As with the bats, when two mice were separated, their brain activity was no longer coupled, researchers report.

This neural synchrony might underpin some social behaviors, such as grooming each other or fighting. Just before bats interacted, their brain activity became more coordinated. Brain synchrony also appeared to be a factor in contests of dominance between mice. A pushier mouse’s behavior was more likely to spark brain coordination than a meeker mouse’s actions, researchers found.