According to two papers published in the journal Cell, Egyptian fruit bats and mice can 'sync' brainwaves in social situations. The neural activity synchronization in the brains of human conversation partners has been revealed previously as a result of one individual picking up social cues from the other and modulating their behavior based on those cues. Now, these studies suggest that something similar occurs when animals engage in natural social interactions and discover that some aspects of the animals' social behavior can be predicted based on neural observations.
The senior author of one of the papers, Michael Yartsev of the Department of Bioengineering at the University of California, Berkeley, said that animal models are quite essential for being able to study brain phenomena at levels that scientists can't ordinarily access in humans. Since bats are incredibly social and naturally live in highly complex social environments, they are a great model for dealing with critical scientific questions about social behavior and the neural mechanisms underlying it.
The senior author of the second paper, Weizhe Hong of the Departments of Biology Chemistry and Neurobiology at the University of California, Los Angeles, said that if one thinks of the brain like a black box that receives input and gives output in response, studying social interactions is similar to trying to understand how the output of one box provides input to another, and how those boxes work together and create a loop. The team's research in mice allows them to peer inside those black boxes and get a better look at the internal machinery.
The group from Berkeley monitored the bats for sessions of about 100minutes each as they engaged in a wide range of natural social interactions such as grooming, mating, and fighting. They filmed the bats with high-speed cameras, and they carefully characterized their specific behaviors and interactions.
It was a different tack for the team from UCLA. The team used a device called a miniaturized microendoscope to monitor the brain activities of mice during social situations. These tiny devices weight two grams and are fitted on the mice, which allow the researchers to track the activity of hundreds of neurons at the same time in both animals. The team identified mice exhibiting interbrain correlations in natural social interactions where animals freely interact with each other. Furthermore, the access to thousands of individual neurons gave the researchers a unique view of both animals' decision-making processes and revealed that interbrain correlation emerges from different sets of neurons that encode one's behavior and behavior of the social partner.
Lyle Kingsbury, a graduate student in Hong's lab and first author of the mouse paper, noted they know that social interactions are altered in many mental diseases in human, including autism spectrum disorders and schizophrenia. Developing a genetically tractable model system opens up the possibility of exploring how interbrain synchrony is disrupted in people with these conditions and may provide new information about possible interventions.
