Inferior frontal gyrus hemodynamic activity synchronizes between subjects engaging in face-to-face communication
Even though humans have evolved to communicate face-to-face, life in modern societies involves communication via email and phone to an increasingly large extent, and time spent on face-to-face communications is becoming less frequent. In contrast to these other forms of communication, face-to-face communication is characterized by rich audiovisual stimulation and non-verbal cues such as facial expressions and gestures that further provide cues for turn taking during conversations. It has been an open question, however, whether there are neurocognitive mechanisms that are specifically activated during face-to-face (and not during other forms of) interpersonal communication.
In their recent study, Jiang et al. (2012) recorded hemodynamic brain activity using near-infrared spectroscopy simultaneously from 10 pairs of interacting subjects to study whether there are brain responses that are elicited in synchrony in the interacting subjects' brains only during face-to-face communication. More specifically, their subjects engaged in face-to-face dialogue, face-to-face monologue, back-to-back dialogue, and back-to-back monologue while their brain hemodynamic activity was recorded. The authors observed synchronization of hemodynamic activity in the inferior frontal gyrus among the conversing subject pairs that was specific to face-to-face conversation. A further analysis of the dynamics of inferior frontal gyrus synchronization suggested that the activity was due to face-to-face interactions such as turn-taking behavior rather than mere verbal signal transmission.
These findings suggest that face-to-face communication involves interpersonal brain activity patterns that other types of communication lack. These novel findings are highly interesting also from the perspective that simultaneous recording of brain activity from two interacting subjects has become a very exciting area of research (that is often referred to as two-person neuroscience or hyperscanning), and Jiang et al. (2012) demonstrate in their study that the approach can indeed be utilized to capture neuroscientifically interesting phenomena that take place specifically during two-person interactions.