Face to Face, Brain to Brain: Exploring the Mechanisms of Dyadic Social Interactions

Cognition materializes in an interpersonal space. The emergence of complex behaviors requires the coordination of actions among individuals according to a shared set of rules. Despite the central role of other individuals in shaping our minds, experiments typically isolate human or animal subjects from their natural environment by placing them in a sealed quiet room where interactions occur solely with a computer screen. In everyday life, however, we spend most of our time interacting with other individuals. In the talk I will argue in favor of a shift from a single-brain to a multi-brain frame of reference. I will present a new analysis tool, in which we compute the “functional coherence” between the brain responses in a seed area in one subject and the responses in other subjects’ brains. While at rest we see no correlations in the responses across subjects, during the processing of real life stimuli the brain responses in one brain are coupled to the responses in another brain. Such neural coupling is mediate via the transmission of a signal (stimulus-to-brain coupling) through the environment. When the transmitted signal is speech signal which was produced by another brain, the inter-subject functional coherence analysis exposes a shared neural substrate that exhibits temporally aligned response patterns across the speaker and the listener. The recording of the neural responses from two brains opens a new window into the neural basis of interpersonal communication, and may be used to assess verbal and non-verbal forms of interaction in both human and other model systems.