Abstract: Hyperscanning approach is a type of neuroimaging technique. It refers to measure neural activities simultaneously from two or more agents who are involved in the same social interactions, and then inter-brain coupling (or interpersonal neural synchronization, INS) is analyzed and used to explain brain-to-brain neural correlates of social interactions in the perspective of group level. During the past decade, hyperscanning approach became more and more popular, and has been one of powerful approaches to elucidate intrinsic property of higher cognition with social interactions in condition of higher ecological validity, such as cooperation/competition, behavioral synchrony/imitation, interpersonal communication and economic decision-makings so on. In this paper, we first review and summarize the previous hyperscanning studiesover the past decade, which followed by limitations and future studies on other research fields with social interaction. First, cooperation and competition are fundamental, but pivotal, requirement for survival in human beings (even in animals). Enhanced interpersonal neural synchronization (INS)is consistently obtained in prefrontal cortex (PFC) and/or temporal-parietal junction (TPJ) during two participants perform both the concurrent cooperation task (such as jointkey-press task) and the turn-taking cooperation/competition task (such as disk-game task), while absent or much lower INS was found in control condition. Such evidenceindicates that INS could serve as a neuromarker to depict the cooperation and competition behaviors in social context.Moreover, genders and relationship between interacting agents have been shown to significantly affect prefrontal INS and then social interactions. Second, stronger INS emergesin PFC and/or right TPJ with better coordination performances during singing, instrument playing and game of charades. More interestingly, several pieces of evidence show INS iscorrelated with the empathyand shared knowledge. Third, enhanced prefrontal INS is also observed in the interpersonal communication task (face-to-face verbal communication task, emotional transmission and so on). Further, INS could predict verbal and/or non-verbal communication quality, such as teacher-student interactions during teaching, leader emergence during a non-leader group discussion task. Forth, prefrontal INS has also found in economic games (such as trust game, prisoner's dilemma, et al.) and spontaneous deception so on. To summarize, interpersonal neural synchronization in widely-distributed network in the brain, especially in fronto-parietal network, could explain social interaction in the group level, which gives us a deep understanding the nature of social interaction from the level of sensation/motion, decision making and information transmission. However, the limitations on hyperscanning studies should also be mentioned. First,portable equipment and much higher-resolution fNIRS equipment arerequired to be used in many types of natural social interactions. Second, eye movement and physiological activities are important in social interactions, a multimodal hyperscanning platform with combination of behavioral, physiological, eye movement and brain data needs to be developed. Finally and most importantly, an optimal mathematical model should be built up based on multiple levels of data, which can help us to understand the nature of interpersonal neural synchronization and intrinsic property of social interaction. Finally, hyperscanning approach should have huge potentials in both scientific research and clinic applications, such as dynamic evaluation of teaching quality, dynamic evaluation of psychological counseling, measurement of social function deficiency and optimizing inference resolution in patients with autisms, and schizophrenia so on.

Key words: Social interaction, Hyperscanning, Interpersonal neural synchronization, Neuromarker

摘要： 超扫描技术可同时记录多名被试在同一认知活动中的脑活动，并通过分析脑间活动同步及其与行为指标间的关系描述社会互动的群体脑机制。本文总结了近十多年超扫描研究在合作与竞争、动作和行为同步、人际交流等领域的成果，在已有研究基础上指出脑间活动同步可刻画社会互动中感觉运动、思维决策以及信息传递等三大层面上的互动情况，可能成为社会互动活动的神经标记，并阐述了超扫描技术研究的局限性及其研究展望与应用潜能。

关键词: 社会互动, 超扫描技术, 脑间活动同步, 神经标记