So it turns out that like humans, animals’ brains sync up with one another during social interactions. This, according to new research examining the neural activity of Egyptian fruit bats and mice engaging within their respective social groups.
We already know from prior research there is synchronization of neural activity in humans’ brains during social activities such as conversation when one person picks up social cues from the other and modulates his or her own behavior based on those cues. Now there is evidence the same thing occurs with nonhuman animals–especially with animals that are highly social by nature like bats and mice.
The synced-up bat study overview
Researchers monitored the bats for sessions of about 100 minutes each as they engaged in a wide range of natural social interactions, such as grooming, mating, and fighting. The bats were filmed with high-speed cameras, and their specific behaviors and interactions were carefully characterized.
As this was happening, the scientists were using a technology called wireless electrophysiology to simultaneously record the brain activity in the bats’ frontal cortices across a wide range of neural signals, ranging from brain oscillations to individual neurons and local neural populations. They saw that the brains of different bats became highly correlated and that this correlation was most pronounced in the high-frequency range of brain oscillations. Furthermore, the correlation between the brains of individual bats extended across multiple timescales of social interactions, ranging from seconds to hours. Remarkably, by looking at the level of correlation, they could predict whether the bats would initiate social interactions or not.
The in-sync mice study overview
Researchers used a device called a miniaturized microendoscope to monitor the brain activities of mice during social situations. These tiny devices, which weigh only two grams, are fitted on the mice and allow the researchers to monitor the activity of hundreds of neurons at the same time in both animals. They saw that mice also exhibit interbrain correlations in natural social interactions where animals freely interact with each other. Moreover, the access to thousands of individual neurons gave them an unprecedented view of both animals’ decision-making processes and revealed that interbrain correlation emerges from different sets of neurons that encode one’s own behavior and behavior of the social partner.
Social interactions are often nested within the context of a dominance hierarchy. By imaging two mice in a competitive social interaction, they discovered that behavior of the dominant animal drives synchrony more strongly than behavior of the subordinate animal. Remarkably, they also found that the level of correlation between two brains predicts how mice will respond to each other’s behavior as well as the dominance relationships that develop between them.
Journal Reference: Wujie Zhang, Michael M. Yartsev. Correlated Neural Activity across the Brains of Socially Interacting Bats. Cell, 2019;
Journal Reference: Lyle Kingsbury, Shan Huang, Jun Wang, Ken Gu, Peyman Golshani, Ye Emily Wu, Weizhe Hong. Correlated Neural Activity and Encoding of Behavior across Brains of Socially Interacting Animals. Cell, 2019;