how-to-calculate-validate-inter-brain-synchronization-fnirs

How to Calculate and Validate Inter-brain Synchronization in a fNIRS Hyperscanning Study

The dynamics between coupled brains of individuals have been increasingly represented by inter-brain synchronization (IBS) when they coordinate with each ...

functional-near-infrared-spectroscopy-hyperscanning-study

Functional Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling

Functional Near-Infrared Spectroscopy (fNIRS) hyperscanning is an innovative technique that enables real-time monitoring of brain activity among multiple ...

East China Normal University

east china normal university

Shanghai Normal University

People tend to be more prosocial after synchronizing behaviors with others, yet the underlying neural mechanisms are rarely known. In this study, participant dyads performed either a coordination task or an independence task, with their brain activations recorded via the functional near-infrared spectroscopy hyperscanning technique. Participant dyads in the coordination group showed higher synchronized behaviors and greater subsequent inclination to help each other than those in the independence group, indicating the prosocial effect of interpersonal synchrony. Importantly, the coordination group demonstrated the significant task-related brain coherence, namely the interbrain synchronization, at the left middle frontal area. The detected interbrain synchronization was sensitive to shared intentionality between participants and was correlated with the mutual prosocial inclination. Further, the task-related brain coherence played a mediation role in the prosocial effect of interpersonal synchrony. This study reveals the relevance of brain-to-brain synchronization among individuals with subsequent mutual prosocial inclination and suggests the neural mechanism associating with shared cognition for the facilitation of interpersonal synchrony on prosociality.

Brain-to-brain synchronization across two persons predicts mutual prosociality.

People could behave in two different ways when engaging in interpersonal coordination activities: moving at the same frequency (isofrequency pattern, IP; the movement frequency ratio is 1:1) or at different frequencies (multifrequency pattern, MP; the movement frequency ratio is non 1:1). However, how the interpersonal coordination pattern modulates coordination outcome and the related brain-to-brain connectivity is not fully understood. Here, we adopted a continuous joint drawing task in which two participants co-drew parallelogram shapes according to two coordination patterns (i.e., IP vs. MP) while their brain activities were simultaneously recorded by the functional near-infrared spectroscopy (fNIRS) based hyperscanning technique. Dyads showed better coordination performance, as well as relatively greater interpersonal brain synchronization (IBS) at the left frontopolar area, in the MP condition compared to the IP condition. Granger causality analyses further disclosed the bidirectional influences between the brains of the coordinating individuals. Such interpersonal influences were enhanced when individuals coordinated in the MP condition. Finally, the IBS during coordination was related to the dyadic self-control level. Taken together, our study revealed that interpersonal multifrequency coordination pattern facilitates the coordination efficiency, which was associated with the enhanced brain-to-brain connectivity. Our work also suggests the potentially positive role of self-control during the interpersonal coordination process.

Coordination Elicits Synchronous Brain Activity Between Co-actors: Frequency Ratio Matters.

Why is some music well-received whereas other music is not? Previous research has indicated the close temporal dependencies of neural activity among performers and among audiences. However, it is unknown whether similar neural contingencies exist between performers and audiences. Here, we used dual near-infrared spectroscopy (NIRS) to assess whether inter-brain synchronization between violinist and audience underlies the popularity of violin performance. In the experiment, individual audience members (16 females) watched pre-recorded videos, each lasting 100 ​s or so, in which a violinist performed 12 musical pieces. The results showed that the popularity of the performance correlated with the left-temporal inter-brain coherence (IBC) between the audience and the violinist. The correlation was stronger at late watching (>50 ​s) than at early watching (≤50 ​s). The smaller the Granger causality from the audience to the violinist was, the higher was the popularity of the piece with the audience. Discriminant analysis showed that the IBC could distinguish high popularity from low popularity. Further analysis using support vector regression showed that the IBC could also predict the popularity. These findings reveal the association of IBC with the popularity of violin performance. Music appreciation involves the brains of music producers and perceivers in a temporally aligned network through which audiences perceive the intentions of the performer and show positive emotions related to the musical performance.

The averaged inter-brain coherence between the audience and a violinist predicts the popularity of violin performance.

Recent neuroimaging research has suggested that unequal cognitive efforts exist between interpreting from language 1 (L1) to language 2 (L2) compared with interpreting from L2 to L1. However, the neural substrates that underlie this directionality effect are not yet well understood. Whether directionality is modulated by interpreting expertise also remains unknown. In this study, we recruited two groups of Mandarin (L1)/English (L2) bilingual speakers with varying levels of interpreting expertise and asked them to perform interpreting and reading tasks. Functional near-infrared spectroscopy (fNIRS) was used to collect cortical brain data for participants during each task, using 68 channels that covered the prefrontal cortex and the bilateral perisylvian regions. The interpreting-related neuroimaging data was normalized by using both L1 and L2 reading tasks, to control the function of reading and vocalization respectively. Our findings revealed the directionality effect in both groups, with forward interpreting (from L1 to L2) produced more pronounced brain activity, when normalized for reading. We also found that directionality was modulated by interpreting expertise in both normalizations. For the group with relatively high expertise, the activated brain regions included the right Broca's area and the left premotor and supplementary motor cortex; whereas for the group with relatively low expertise, the activated brain areas covered the superior temporal gyrus, the dorsolateral prefrontal cortex (DLPFC), the Broca's area, and visual area 3 in the right hemisphere. These findings indicated that interpreting expertise modulated brain activation, possibly because of more developed cognitive skills associated with executive functions in experienced interpreters.

Optical Mapping of Brain Activity Underlying Directionality and Its Modulation by Expertise in Mandarin/English Interpreting.

Self-face advantage refers to adults' response to self-face is faster than that to other-face. A stop-signal task was used to explore how self-face advantage interacted with response inhibition. The results showed that reaction times of self-face were faster than that of other-face not in the go task but in the stop response trials. The novelty of the finding was that self-face has shorter stop-signal reaction time compared to other-face in the successful inhibition trials. These results indicated the processing mechanism of self-face may be characterized by a strong response tendency and a corresponding strong inhibition control.

Withholding response to self-face is faster than to other-face.

Numerous studies have shown there exist attention biases for self-related and negative stimuli. Few studies, however, have been carried out to compare the effects of such stimuli on the neural mechanisms of early attentional alertness and subsequent cognitive processing. The purpose of the present study was to examine the temporal primacy of both self-related stimuli and negative stimuli in the neurophysiologic level. In a modified oddball task, event-related potentials of the deviant stimuli (i.e., self-face, negative face and neutral face) were recorded. Results revealed that larger P2 amplitudes were elicited by self-related and negative stimuli than by neutral stimuli. Negative stimuli, however, elicited shorter P2 latencies than self-related and neutral stimuli. As for the N2 component, self-related and negative stimuli elicited smaller amplitudes and shorter latencies than neutral stimuli, but otherwise did not differ. Self-related stimuli also elicited larger P3 and late positive component (LPC) amplitudes than negative and neutral stimuli. The pattern of results suggests that the primacy of negative stimuli occurred at an early attention stage of processing, while the primacy of self-related stimuli occurred at the subsequent cognitive evaluation and memory stage.

The temporal primacy of self-related stimuli and negative stimuli: an ERP-based comparative study.

The damaging effect of threat on creativity has been confirmed by many studies. However, the neural mechanism underlying this effect has not been clarified. We designed an experiment to explore changes in brain activation when creativity is threatened. Specifically, participants performed the Chinese Remote Associates Test (RAT) under three conditions. The control condition was accompanied by no sound, the neutral condition was accompanied by unpredictable neutral sounds, and the threat condition was manipulated through unpredictable aversive sounds. We used functional near-infrared spectroscopy measurements to collect cognitive neurological data. The results showed that the threat condition reduced the accuracy and response time of the RAT and led to individual negative emotions. Participants' prefrontal cortex and supramarginal gyrus activation decreased under threat. These results provide a reference for clarifying the negative impact of threat on creativity and highlight its cognitive neural mechanisms.

Human creativity escapes in the struggle against threat: Evidence from neural mechanisms.

Elderly people tend not to compete with others, and if they do, the mechanism behind the competition is not clear. In this study, groups of elderly couples and matched cross-sex controls were recruited to perform a competitive button-pressing task, while their brain signals were simultaneously collected using functional near-infrared spectroscopy (fNIRS) hyperscanning. Several fundamental observations were made. First, controls showed attenuated interpersonal competition across task processes, but couples held the competition with each other. Second, couples demonstrated increased inter-brain synchronization (IBS) between the middle temporal cortex and the temporoparietal junction across task processes. Third, Granger causality analysis in couples revealed significant differences between the directions (i.e., from men to women, and from women to men) in the first half of the competitive task, whereas there was no significant difference in the second half. Finally, the groups of couples and controls could be successfully discriminated against based on IBS by using a machine-learning approach. In sum, these findings indicate that elderly couples can maintain interpersonal competition, and such maintenance might be associated with changes in the IBS of the mentalizing system. It suggests the possible positive impact of long-term spouse relationships on interpersonal interactions, both behaviorally and neurally, in terms of competition.

Interpersonal Competition in Elderly Couples: A Functional Near-Infrared Spectroscopy Hyperscanning Study.

People frequently share their negative experiences and feelings with others. Little is known, however, about the social outcomes of sharing negative experiences and the underlying neural mechanisms. We addressed this dearth of knowledge by leveraging functional near-infrared spectroscopy (fNIRS) hyperscanning: while dyad participants took turns to share their own (self-disclosure group) or a stranger's (non-disclosure group) negative and neutral experiences, their respective brain activity was recorded simultaneously by fNIRS. We observed that sharing negative (relative to neutral) experiences enhanced greater mutual prosociality, emotional empathy and interpersonal neural synchronization (INS) at the left superior frontal cortex in the self-disclosure group compared to the non-disclosure group. Importantly, mediation analyses further revealed that in the self-disclosure (but not non-disclosure) group, the increased emotional empathy and INS elicited by sharing negative experiences relative to sharing neutral experiences promoted the enhanced prosociality through increasing interpersonal liking. These results indicate that self-disclosure of negative experiences can promote prosocial behaviors via social dynamics (defined as social affective and cognitive factors, including empathy and liking) and shared neural responses. Our findings suggest that when people express negative sentiments, they incline to follow up with positive actions.

Yinying Hu

Institute of Brain and Education Innovation,
School of Psychology and Cognitive Science,
Institute of Brain and Education Innovation, School of Psychology and Cognitive Science

East China Normal University

How to Calculate and Validate Inter-brain Synchronization in a fNIRS Hyperscanning Study

Functional Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling

Yinying Hu

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institute of Brain and Education Innovation,School of Psychology and Cognitive Science,Institute of Brain and Education Innovation, School of Psychology and Cognitive Science

East China Normal University

How to Calculate and Validate Inter-brain Synchronization in a fNIRS Hyperscanning Study

Functional Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling

Institute of Brain and Education Innovation,
School of Psychology and Cognitive Science,
Institute of Brain and Education Innovation, School of Psychology and Cognitive Science