Brain-to-Brain Coupling in the Gamma-Band as a Marker of Shared Intentionality.

Paulo Barraza,Eugenio Rodríguez,Alejandro Pérez

doi:10.3389/fnhum.2020.00295

Abstract

Cooperation and competition are two ways of social interaction keys to life in society. Recent EEG-based hyperscanning studies reveal that cooperative and competitive interactions induce an increase in interbrain coupling. However, whether this interbrain coupling effect is just a reflection of inter-subject motor coordination or can also signal the type of social interaction is unknown. Here, we show that behavioral coordination and social interaction type can be distinguished according to the frequency of oscillation in which the brains are coupled. We use EEG to simultaneously measure the brain activity of pairs of subjects, while they were performing a visual cue-target task in a cooperative and competitive manner. Behavioral responses were quasi-simultaneous between subject pairs for both competitive and cooperative conditions, with faster average response times for the competitive condition. Concerning brain activity, we found increased interbrain coupling in theta band (3–7 Hz) during cooperation and competition, with stronger coupling during competitive interactions. This increase of interbrain theta coupling correlated with a decrease in reaction times of the dyads. Interestingly, we also found an increase in brain-to-brain coupling in gamma band (38–42 Hz) only during cooperative interactions. Unlike the theta coupling effect, the gamma interbrain coupling did not correlate with dyads’ reaction times. Taken together, these results suggest that theta interbrain coupling could be linked to motor coordination processes common to cooperative and competitive interactions, while gamma brain-to-brain coupling emerges as an electrophysiological marker of shared intentionality during cooperative interactions.

Highlights

Cooperation and competition are two forms of social exchange that play a key role in social and cultural life (Tomasello, 2009)
Regarding average response time (RT) per block, we found that during competitive interactions the dyads respond significantly faster in the 2nd block (264.41 ms, SE = 5.50) than in the 1st block (279.76 ms, SE = 4.96) (Z = −3.495, p < 0.0001, r = 0.552) (Figure 2B)
In line with previous studies (Balconi and Vanutelli, 2017b; Liu et al, 2018) our results show an increased theta phase-locking value (PLV) brain-to-brain coupling associated with the social interaction

Summary

Introduction

Cooperation and competition are two forms of social exchange that play a key role in social and cultural life (Tomasello, 2009) In functional terms, both types of social behavior involve mentalization processes (Gallagher et al, 2002; Elliott et al, 2006), but they differ markedly in terms of the intention that motivates the interaction (Tomasello and Carpenter, 2007; Tsoi et al, 2016). Decety et al (2004) used fMRI to evaluate the hemodynamic activity of 12 adults while playing a cooperative or competitive game with a confederate They found that cooperative behavior was selectively associated with orbitofrontal cortex activity, while competitive behavior was associated with inferior parietal and medial prefrontal regions. To achieve a thorough understanding of the neural processes that underlie cooperative and competitive behaviors, it is crucial to elucidate how the brain activity of subjects engaged in social interactions is co-regulated and integrated to produce a flow of shared social experiences

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