EEG Hyperscanning

During the lifespan, humans walk, talk and live together. Research with EEG hyperscanning has found that in social cooperation, brain oscillations adapt to each other.
EEG Neurofeedback is a method for acquiring control over one's own brain waves. It is used as therapy method in ADHD, depression, chronic tinnitus, among others.
In the present work, research with the two methods is reviewed. Then, a study proposal is elaborated for combining EEG hyperscanning with EEG neurofeddback.

Crick and Koch's 1990 "neurobiological theory of consciousness" sparked the race for the physical correlates of subjective experience. 30 years later, cognitive sciences trend toward consideration of the brain's electromagnetic field as the primary seat of consciousness, the "to be" of the individual. Recent advancements in laboratory tools have preceded an influx of studies reporting a synchronization between the neuronally generated EM fields of interacting individuals. An embodied and enactive neuroscientific approach has gained traction in the wake of these findings wherein consciousness and cognition are theorized to be regulated and distributed beyond the individual. We approach this frontier to extend the implications of person-to-person synchrony to propose a process of combination whereby coupled individual agents merge into a hierarchical cognitive system to which they are subsidiary. Such is to say, the complex mammalian consciousness humans possess may not be the tip of the iceberg, but another step in a succeeding staircase. To this end, the axioms and conjectures of General Resonance Theory are utilized to describe this phenomenon of interpersonal resonant combination. Our proposal describes a coupled system of spatially distributed EM fields that are synchronized through recurrent, entraining behavioral interactions. The system, having achieved sufficient synchronization, enjoys an optimization of information flow that alters the conscious states of its merging agents and enhances group performance capabilities. In the race for the neurobiological correlates of subjective experience, we attempt the first steps in the journey toward defining the physical basis of "group consciousness." The establishment of a concrete account of the combination of consciousness at a scale superseding individual human consciousness remains speculation, but our suggested approach provides a framework for empirical testing of these possibilities.

We live in a social world where we interact with each other. Neurofeedback (NFB) is an indispensable element for such interaction. Single-person NFB studies using electroencephalography (EEG) or other neuroimaging recordings were extensively reported. However, hyperscanning studies using inter-brain synchrony (IBS) as an NFB feature are completely unknown. In this study, we present two different experimental designs where IBS was fed visually back either as two balls approaching each other (so-called "ball" design) or as two pendula reflecting oscillatory activity of two participants (so-called "pendulum" design). The NFB was provided at two EEG frequencies (2.5 and 5 Hz) and manipulated by enhanced (fake condition) and inverse feedback. We showed that the participants were able to increase IBS by using NFB, especially when it was fed back at the theta frequency. Apart from the intra-and inter-brain coupling, other oscillatory activities (e.g., power spectral density, peak amplitude and peak frequency) changed during the task compared to rest. Moreover, all the measures showed specific correlations to the subjective post-survey item scores, reflecting subjective feeling and appraisal. We conclude that hyperscanning with IBS as a feedback feature seems to be an important tool to examine neural mechanisms of social interaction and collective behavior.

Much of human learning emerges as a result of interaction with others. Yet, this interpersonal process has been poorly characterized from a neurophysiological perspective. This study investigated (i) whether Interpersonal Brain Synchronization (IBS) can reliably mark social interactive learning, and specifically (ii) during what kind of interactive behavior. We recorded brain activity from learner-instructor dyads using functional Near-Infrared Spectroscopy (fNIRS) during the acquisition of a music song. We made four fundamental observations. First, during the interactive learning task, brain activity recorded from the bilateral Inferior Frontal Cortex (IFC) synchronized across the learner and the instructor. Second, such IBS was observed in particular when the learner was observing the instructor's vocal behavior and when the learning experience entailed a turn-taking and more active mode of interaction. Third, this specific enhancement of IBS predicted learner's behavioral performance. Fourth, Granger causality analyses further disclosed that the signal recorded from the instructor's brain better predicted that recorded from the learner's brain than vice versa. Together, these results indicate that social interactive learning can be neurophysiologically characterized in terms of IBS. Furthermore, they suggest that the learner's involvement in the learning experience, alongside the instructor's modeling, are key factors driving the alignment of neural processes across learner and instructor. Such alignment impacts upon the real-time acquisition of new information and eventually upon the learning (behavioral) performance. Hence, besides providing a biological characterization of social interactive learning, our results hold relevance for clinical and pedagogical practices.