Prefrontal Cortical Synchronization Underlies Emotional State Transmission via Perceived Arousal

Touch is one of the most fundamental and evolutionarily conserved channels of social communication, yet it remains unclear whether and how touch alone can transmit affective states between individuals. Existing studies often conflate tactile contact with visual or auditory cues, obscuring the neural mechanisms and temporal dynamics of emotional state transmission. Here we isolated tactile channel in pairs of participants who engaged in handholding while one partner (Sender) viewed emotional videos and the other (Receiver) was visually and acoustically isolated. Functional near-infrared spectroscopy (fNIRS) hyperscanning revealed that touch aligned partners’ arousal states, enhanced receivers’ sensitivity to emotional cues, and strengthened prefrontal inter-brain synchrony (IBS).Crucially, mediation analyses showed that under the touch level, prefrontal IBS predicted receivers’ arousal estimates, which in turn predicted their emotional sensitivity ($d'$), indicating a touch-specific indirect pathway through arousal alignment.Time-resolved analyses further revealed that neural activity in the Sender's prefrontal cortex, particularly inferior frontal gyrus, preceded Receiver neural responses by approximately 16 s. These findings reveal a neural mechanism by which embodied contact sequentially aligns emotional states through prefrontal coupling. By elucidating how touch embeds emotional meaning within a shared neural space, our findings advance an embodied account of human communication and provide a biological foundation for developing emotionally attuned, socially embedded artificial intelligence.