Spontaneous dyadic behavior predicts the emergence of interpersonal neural synchrony

Koul, A., et al. (2023).

NeuroImage, 277, 120233.

https://doi.org/10.1016/j.neuroimage.2023.120233 

Abstract

Synchronization of neural activity across brains – Interpersonal Neural Synchrony (INS) – is emerging as a powerful marker of social interaction that predicts success of multi-person coordination, communication, and cooperation. As the origins of INS are poorly understood, we tested whether and how INS might emerge from spontaneous dyadic behavior. We recorded neural activity (EEG) and human behavior (full-body kinematics, eye movements, and facial expressions) while dyads of participants were instructed to look at each other without speaking or making co-verbal gestures. We made four fundamental observations. First, despite the absence of a structured social task, INS emerged spontaneously only when participants were able to see each other. Second, we show that such spontaneous INS, comprising specific spectral and topographic profiles, did not merely reflect intra-personal modulations of neural activity, but it rather reflected real-time and dyad-specific coupling of neural activities. Third, using state-of-art video-image processing and deep learning, we extracted the temporal unfolding of three notable social behavioral cues – body movement, eye contact, and smiling – and demonstrated that these behaviors also spontaneously synchronized within dyads. Fourth, we probed the correlates of INS in such synchronized social behaviors. Using cross-correlation and Granger causality analyses, we show that synchronized social behaviors anticipate and in fact Granger cause INS. These results provide proof-of-concept evidence for studying interpersonal neural and behavioral synchrony under natural and unconstrained conditions. Most importantly, the results suggest that INS could be conceptualized as an emergent property of two coupled neural systems: an entrainment phenomenon, promoted by real-time dyadic behavior.

Highlights

• Interpersonal neural synchrony (INS) emerges spontaneously.

• INS only requires individuals to see each other (not a structured social task).

• Spontaneous INS emerges from dyad-specific behavioral synchrony.

• Reciprocated eye contact, body movement and smiling Granger cause INS.

• INS is an emergent property of two coupled neural systems.

The research is here.

Note: It would be interesting to measure the neurosynchronization between psychologist and patient to determine if it could improve psychotherapy outcomes.

Revealing the neurobiology underlying interpersonal neural synchronization with multimodal data fusion

Lotter, L. D., Kohl, S. H.,  et al. (2023).

Neuroscience & Biobehavioral Reviews,

146, 105042. 

https://doi.org/10.1016/j.neubiorev.2023.105042

Abstract

Humans synchronize with one another to foster successful interactions. Here, we use a multimodal data fusion approach with the aim of elucidating the neurobiological mechanisms by which interpersonal neural synchronization (INS) occurs. Our meta-analysis of 22 functional magnetic resonance imaging and 69 near-infrared spectroscopy hyperscanning experiments (740 and 3721 subjects) revealed robust brain regional correlates of INS in the right temporoparietal junction and left ventral prefrontal cortex. Integrating this meta-analytic information with public databases, biobehavioral and brain-functional association analyses suggested that INS involves sensory-integrative hubs with functional connections to mentalizing and attention networks. On the molecular and genetic levels, we found INS to be associated with GABAergic neurotransmission and layer IV/V neuronal circuits, protracted developmental gene expression patterns, and disorders of neurodevelopment. Although limited by the indirect nature of phenotypic-molecular association analyses, our findings generate new testable hypotheses on the neurobiological basis of INS.

Highlights

• When we interact, both our behavior and our neural activity synchronize.

• Neuroimaging meta-analysis and multimodal data fusion may reveal neural mechanisms.

• Robust involvement of right temporoparietal and left prefrontal brain regions.

• Associations to attention and mentalizing, GABA and layer IV/V neurotransmission.

• Brain-wide associated genes are enriched in neurodevelopmental disorders.

Discussion

In recent years, synchronization of brain activities between interacting partners has been acknowledged as a central mechanism by which we foster successful social relationships as well as a potential factor involved in the pathogenesis of diverse neuropsychiatric disorders. Based on the results generated by our multimodal data fusion approach (see Fig. 5), we hypothesized that human INS is tightly linked to social attentional processing, subserved by the rTPJ as a sensory integration hub at the brain system level, and potentially facilitated by GABA-mediated E/I balance at the neurophysiological level.

The research is here.

Note: The interpersonal neural synchronization is a fascinating piece of research.  How to improve the synchronization may help with effective psychotherapy.