# Electrophysiological Hyperscanning of Negotiation During Group-Oriented Decision-Making
## 4 Discussion
Moreover, previous work on social bargaining showed how alpha oscillations could serve as a mechanism by which different brain areas flexibly interact in order to adapt ongoing behavior in socially demanding contexts [21]. Temporaparietal regions are also involved in social cognition and communication [40], managing social dynamics, including negotiation processes [41,42]. Given that alpha suppression in posterior regions has been previously associated with enhanced cognitive performance [30], a possible interpretation can be that this reduction in alpha power in the temporo-central regions, compared to the frontal ones, marks the cognitive effort derived from the negotiation process in our sample of participants. The study also found that beta and gamma activity was more prominent in the parieto-occipital region compared to the frontal and temporo-central regions. Since beta and gamma oscillations are associated with cognitive control, memory integration, and decision-making [34,35], their increased presence in parieto-occipital areas suggests that negotiation requires the integration of multiple perspectives and the monitoring of shared goals. Elevated beta and gamma power in these regions may reflect working memory demands and the multimodal integration of verbal and social cues, alongside the on going evaluation of semantic relevance--key processes for managing complex, dialogic interactions in which information must be actively maintained and dynamically updated. Secondly, at the dyadic level, the analysis revealed significant patterns of dissimilarity within the dyads. Specifically, and differently from what hypothesized, the Euclidean Distance analysis indicated greater dissimilarity in delta band activity in the frontal region compared to other brain regions. The increased dissimilarity in delta band activity likely reflects divergent cognitive and affective states between interactants rather than uniform synchronization. Delta oscillations, particularly in frontal regions, are implicated in large-scale neural coordination, executive control, and predictive coding in social contexts [54]. The observed increase in frontal delta dissimilarity, contrary to classic models of inter-brain synchrony during cooperation, may reflect individualized engagement of top-down regulatory processes such as conflict monitoring, prediction updating, or fairness evaluation--each governed independently in real time. This dissociation aligns with emerging views that cooperation does not always entail neural alignment but may also involve parallel regulatory roles within a shared social frame. While previous studies have reported frontal delta synchrony during joint tasks, the negotiation paradigm used in this paper emphasizes strategic divergence and autonomous cognitive control. Thus, the inter-brain dissimilarity in delta activity may reflect asynchronous but complementary activation of conflict regulation and decision evaluation circuits, independently engaged by each partner under shared but non-identical cognitive loads [55]. Unlike mid- and high-frequency bands, delta activity is critical for integrating top-down regulatory mechanisms essential for decision-making and social evaluation [54,56]. The higher dyadic dissimilarity in frontal delta activity, compared to the temporo-central and parieto-occipital regions, may reflect the distinct functional roles of these areas in social interactions. The temporo-central and parieto-occipital regions facilitate the processing of social cues, such as speech prosody and facial expressions, supporting higher synchronization through perceptual-motor mirroring [57]. In contrast, the frontal cortex is engaged in executive functions, including conflict monitoring, strategic adaptation, and inhibition of prepotent responses, which are inherently more individualized and context dependent [58].