Shaping inter-brain plasticity: A feasibility study of enhancing inter-brain synchrony with dyadic neurofeedback

Inter-brain synchrony, the co-activation of brain regions between interacting individuals, is increasingly recognized as a key mechanism underlying social connectedness. This study examined whether dyadic neurofeedback training can enhance inter-brain synchrony in the inferior frontal gyrus and causally increase connectedness. We developed a real-time dyadic neurofeedback platform using functional near-infrared spectroscopy, where unacquainted dyads underwent three training sessions receiving either real neurofeedback or sham feedback. Although we initially anticipated a gradual increase across sessions, the neurofeedback group showed a significant enhancement in IFG inter-brain synchrony only in the third session, with effects extending to additional regions. These neural changes coincided with increased feelings of connectedness and shifts in intra-brain co-activation. While the precise strategies underlying dyadic regulation remain unclear, and additional sessions are needed to fully characterize the learning trajectory, the present findings provide preliminary evidence for the plasticity of inter-brain synchrony and its potential relevance for improving social outcomes.