Interpersonal brain synchronization in the right temporo-parietal junction during face-to-face economic exchange.

In daily life, interpersonal interactions are influenced by uncertainty about other people's intentions. Face-to-face (FF) interaction reduces such uncertainty by providing external visible cues such as facial expression or body gestures and facilitates shared intentionality to promote belief of cooperative decisions and actual cooperative behaviors in interaction. However, so far little is known about interpersonal brain synchronization between two people engaged in naturally occurring FF interactions. In this study, we combined an adapted ultimatum game with functional near-infrared spectroscopy (fNIRS) hyperscanning to investigate how FF interaction impacts interpersonal brain synchronization during economic exchange. Pairs of strangers interacted repeatedly either FF or face-blocked (FB), while their activation was simultaneously measured in the right temporo-parietal junction (rTPJ) and the control region, right dorsolateral prefrontal cortex (rDLPFC). Behaviorally, FF interactions increased shared intentionality between strangers, leading more positive belief of cooperative decisions and more actual gains in the game. FNIRS results indicated increased interpersonal brain synchronizations during FF interactions in rTPJ (but not in rDLPFC) with greater shared intentionality between partners. These results highlighted the importance of rTPJ in collaborative social interactions during FF economic exchange and warrant future research that combines FF interactions with fNIRS hyperscanning to study social brain disorders such as autism.

Tang H ，Mai X ，Wang S ，Zhu C ，Krueger F ，Liu C ... -  《-》

Brain activation and adaptation of deception processing during dyadic face-to-face interaction.

Though deception is consistently characterized by the slippery-slope effect, i.e., the escalation of small lies over time, differing interactive situations and interacting processes may influence the trajectories of deception. To explore this influence, we investigated naturalistic face-to-face (FF) and computer-mediated face-blocked (FB) interactions using functional near-infrared spectroscopy (fNIRS). Pairs of participants acted as deceivers and receivers in an adapted ultimatum game while brain activity in the right dorsolateral prefrontal cortex (rDLPFC) and temporoparietal junction (rTPJ) was recorded. Comparison of deception in the two types of interactions showed that the FF interactions resulted in more successful deception, as well as acceptance of deception, and prompted more neural activation in the rDLPFC than the FB interactions. We found that the deception magnitude escalated in both FF and FB interactions, but rDLPFC activity during deception diminished over time only in the FF interactions but not in FB interactions, suggesting that the deceivers behaviourally adapted to deception over time in both types of interactions, but the neural adaptation occurred only in the FF interactions. Furthermore, neural adaptation in FF interactions was associated with behavioural switching after deception, indicating that the rDLPFC contributes to deception adaptation and the control of switching between deception and honesty. The FF interactions were also characterized by activity in the rTPJ, which showed an adaptation to deception. These findings highlight the importance of interactive situations in dyadic naturalistic settings for deception and the role of the rDLPFC and rTPJ in the slippery-slope effect in deception.

Tang H ，Zhang S ，Jin T ，Wu H ，Su S ，Liu C ... -  《-》

Social risky decision-making reveals gender differences in the TPJ: A hyperscanning study using functional near-infrared spectroscopy.

Previous neuroscience studies have investigated neural correlates of risky decision-making in a single-brain frame during pseudo social (predominantly non face-to-face) contexts. To fully understand the risky decision-making behavior in more natural social interactions, the present study employed a functional near-infrared spectroscopy (fNIRS) hyperscanning technique to simultaneously measure pairs of participants' fronto-temporal activations in a face-to-face gambling card-game. The intra-brain results revealed that both those who identified as males and as females showed higher activations in their mPFC and in the inferior parts of the frontopolar area, as well as in the tempo-parietal junction (TPJ) in cases involving higher versus lower risk. This is consistent with previous findings suggesting importance of the mentalizing network in decision tasks. The fNIRS results of inter-brain neural synchronization (INS) also revealed that males and females showed increased inter-brain coherence in the mPFC and dlPFC. Females, however, uniquely showed increased inter-brain coherence in the left TPJ. This INS result suggests that males may primarily depend on non-social cognitive ability to make a risky decision in a social interaction, while females may use both social and non-social cognitive abilities. The implications are also discussed for general topics of human interaction and two-person neuroscience.

Zhang M ，Liu T ，Pelowski M ，Jia H ，Yu D ... -  《-》

Interpersonal frontopolar neural synchronization in group communication: An exploration toward fNIRS hyperscanning of natural interactions.

Research of interpersonal neural synchronization (INS) using functional near-infrared spectroscopy (fNIRS) hyperscanning is an expanding nascent field. This field still requires the accumulation of findings and establishment of analytic standards. In this study, we therefore intend to extend fNIRS-based INS research in three directions: (1) verifying the enhancement of frontopolar INS by natural and unstructured verbal communication involving more than two individuals; (2) examining timescale dependence of the INS modulation; and (3) evaluating the effects of artifact reduction methods in capturing INS. We conducted an fNIRS hyperscanning study while 12 groups of four subjects were engaged in cooperative verbal communication. Corresponding to the three objectives, our analyses of the data (1) confirmed communication-enhanced frontopolar INS, as expected from the region's roles in social communication; (2) revealed the timescale dependency in the INS modulation, suggesting the merit of evaluating INS in fine timescale bins; and (3) determined that removal of the skin blood flow component engenders substantial improvement in sensitivity to communication-enhanced INS and segregation from artifactual synchronization, and that caution for artifact reduction preprocessing is needed to avoid excessive removal of the neural fluctuation component. Accordingly, this study provides a prospective technical basis for future hyperscanning studies during daily communicative activities.

Nozawa T ，Sasaki Y ，Sakaki K ，Yokoyama R ，Kawashima R ... -  《-》

Role of the right inferior frontal gyrus in turn-based cooperation and competition: A near-infrared spectroscopy study.

Interpersonal interaction can be classified into two types: concurrent and turn-based interaction, requiring synchronized body-movement and complementary behaviors across persons, respectively. To examine the neural mechanism of turn-based interaction, we simultaneously measured paired participants activations in their bilateral inferior frontal gyrus (IFG) and the bilateral inferior parietal lobule (IPL) in a turn-taking game using near-infrared spectroscopy (NIRS). Pairs of participants were assigned to either one of two roles (game builder and the partner) in the game. The builder's task was to make a copy of a target disk-pattern by placing disks on a monitor, while the partner's task was to aid the builder in his/her goal (cooperation condition) or to obstruct it (competition condition). The builder always took the initial move and the partner followed. The NIRS data demonstrated an interaction of role (builder vs. partner) by task-type (cooperation vs. competition) in the right IFG. The builder in the cooperation condition showed higher activation than the cooperator, but the same builder in the competition condition showed lower activation than in the cooperation condition. The activations in the competitor-builder pairs showed positive correlation between their right IFG, but the activations in the cooperator-builder pairs did not. These results suggest that the builder's activation in the right IFG is reduced/increased in the context of interacting with a cooperative/competitive partner. Also, the competitor may actively trace the builder's disk manipulation, leading to deeper mind-set synchronization in the competition condition, while the cooperator may passively follow the builder's move, leading to shallower mind-set synchronization in the cooperation condition.

Liu T ，Saito H ，Oi M 《-》