Researchers are discovering synchrony in humans and other species, and they are mapping its choreography (its rhythm, timing and undulations) to better understand what benefits it may give us. They are finding evidence that interbrain synchrony prepares people for interaction and beginning to understand it as a marker of relationships. Given that synchronized experiences are often enjoyable, researchers suspect this phenomenon is beneficial: it helps us interact and may have facilitated the evolution of sociality. This new kind of brain research might also illuminate why we don't always click with someone or why social isolation is so harmful to physical and mental health.
Looking at synchrony between bands of brain waves is one way of understanding what's going on between interacting brains. Another is to look at the activity of specific neurons. Using a technology called microendoscopic calcium imaging, which measures changes in induced fluorescence in individual neurons, researchers looked at hundreds of neurons at the same time. In pairs of interacting mice, they established that synchrony appeared during an ongoing social interaction. Further, synchrony in mouse brains arose from separate populations of cells in the prefrontal cortex. With synchrony and other levels of neural interaction, humans teach and learn, forge friendships and romances, and cooperate and converse.
More information:
https://www.scientificamerican.com/article/brain-waves-synchronize-when-people-interact/