Inter-Brain Synchronization via Hyperscanning and Frontoparietal Network Modulation During Social Cooperation in Healthy Adults: A Systematic Review

Background/Objectives: Inter-brain synchronization (IBS) has emerged as a key indicator of social cognition, reflecting the temporal alignment of neural activities across individuals. This systematic review aimed to determine the neurophysiological markers of inter-brain synchronization and the modulation of Frontoparietal Networks during social cooperation tasks in healthy adults. Methods: Following PRISMA 2020 guidelines, a search was executed across Scopus, Web of Science, PubMed, and APA PsycInfo. Hyperscanning studies using EEG, fNIRS, or dual fMRI that evaluated dyads in cooperative contexts were selected based on the PICO framework, with methodological quality rigorously assessed through the MMAT. Results: Eleven studies were included, predominantly utilizing fNIRS (72.7%) and undirected statistical coupling metrics. The data reveal a recurring spatial convergence in key nodes of the Frontoparietal Network (FPN), the Mirror Neuron System (MNS), and the Theory of Mind (ToM) network (IFG, dlPFC, rTPJ, and precuneus) during social cooperation conditions. Although evidence suggests preliminary inter-brain coupling within these networks during social cooperation, the high methodological heterogeneity of the studies precludes the establishment of a definitive causal mechanism. Conclusions: Therefore, inter-brain synchronization should be interpreted as an associative correlate and shared computational task state that requires greater experimental and instrumental standardization in future research.