Hyperscanning neuroimaging technique to reveal the “two-in-one” system in social interactions

AbstractUsing a technique for measuring brain activity simultaneously from two people, known as hyperscanning, we can calculate inter-brain neural effects that appear only in interactions between individuals. Hyperscanning studies using fMRI are advantageous in that they can precisely determine the region(s) involved in inter-brain effects. However, it is almost impossible to record inter-brain effects in daily life. By contrast, hyperscanning EEG studies have high temporal resolution and could be used to capture moment-to-moment interactions. In addition, EEG instrumentation is portable and easy to wear, offering the opportunity to record inter-brain effects during daily-life interactions. However, the disadvantage of this approach is that it is difficult to localize the epicenter of the inter-brain effect. fNIRS has better temporal resolution and portability than fMRI, but has limited spatial resolution and a limited ability to record deep brain structures. Future studies should employ hyperscanning EEG–fMRI, because this approach combines the high temporal resolution of EEG with the high spatial resolution of fMRI. Hyperscanning EEG–fMRI allows us to use inter-brain effects as neuromarkers of the properties of social interactions in daily life. We also wish to emphasize the need to develop a mathematical model explaining how two brains can exhibit synchronized activity