The phi complex as a neuromarker of human social coordination

Abstract

Many social interactions rely upon mutual information exchange: one member of a pair changes in response to the other while at the same time producing actions that alter the behavior of the other. However, little is known about how such social processes are integrated in the brain. Here, we used a specially designed dual-electroencephalogram system and the conceptual framework of coordination dynamics to identify neural signatures of effective, real-time coordination between people and its breakdown or absence. High-resolution spectral analysis of electrical brain activity before and during visually mediated social coordination revealed a marked depression in occipital alpha and rolandic mu rhythms during social interaction that was independent of whether behavior was coordinated or not. In contrast, a pair of oscillatory components (phi₁ and phi₂) located above right centro-parietal cortex distinguished effective from ineffective coordination: increase of phi₁ favored independent behavior and increase of phi₂ favored coordinated behavior. The topography of the phi complex is consistent with neuroanatomical sources within the human mirror neuron system. A plausible mechanism is that the phi complex reflects the influence of the other on a person's ongoing behavior, with phi₁ expressing the inhibition of the human mirror neuron system and phi₂ its enhancement.

• brain oscillations
• electroencephalography
• mirror neuron system
• phi rhythm
• coordination dynamics