When two is better than one: intra and inter-brain connectivity during cooperation

Objective Inter-brain coherence during cooperative joint actions is a main focus of interest for social neuroscientists, but the differential contribution of intra-brain and inter-brain connectivity is still an open question. Also, the possible influence of some psychological variables has not been considered during hyperscanning studies, but deserves to be explored. For example, the self-perceived efficacy during joint actions could modulate the motivational and cognitive processes towards the adoption of common strategies. Participants and methods To do so, in the present study an external feedback was administered during a social interaction in a way to manipulate the perceived efficacy during the adoption of common strategies within the couple. The task consisted in an attentional task presented as a cooperative game in which 24 participants coupled in 12 dyads continuously received reinforcing feedbacks. Meanwhile, their cognitive performance and neural activity were simultaneously recorded by means of functional Near-Infrared Spectroscopy (fNIRS). Optodes were placed over the frontal and prefrontal areas with a 8-channels array. Then, intra and inter-brain connectivity indices were calculated, together with a ConIndex (inter-brain/intra-brain connectivity). Finally, correlational measures were performed to assess the relation between these different levels. Results Results showed that the external feedback was able to influence participants’ responses in both behavioral and neural components in the form of faster RTs and increased connectivity (both inter-brain connectivity and ConIndex) after the social reinforce, mainly localized within the dorsolateral prefrontal cortex. Moreover, the presence of significant correlations between RTs and inter-brain connectivity revealed that only a “two-players dynamic” may induce a significant increased performance. Conclusion The present study provided significant contribution to the identification of patterns of intra and inter-brain functional connectivity with an original focus on the effects of social reinforces provided within dyads of participants cooperating together.