Interpersonal coordination enhances brain-to-brain synchronization and influences responsibility attribution and reward allocation in social cooperation

Closed-Loop Wearable Device Network of Intrinsically-Controlled, Bilateral Coordinated Functional Electrical Stimulation for Stroke

Innovative functional electrical stimulation has demonstrated effectiveness in enhancing daily walking and rehabilitating stroke patients with foot drop. However, its lack of precision in stimulating timing, individual adaptivity, and bilateral symmetry, resulted in diminished clinical efficacy. Therefore, a closed-loop wearable device network of intrinsically controlled functional electrical stimulation (CI-FES) system is proposed, which utilizes the personal surface myoelectricity, derived from the intrinsic neuro signal, as the switch to activate/deactivate the stimulation on the affected side. Simultaneously, it decodes the myoelectricity signal of the patient's healthy side to adjust the stimulation intensity, forming an intrinsically controlled loop with the inertial measurement units. With CI-FES assistance, patients' walking ability significantly improved, evidenced by the shift in ankle joint angle mean and variance from 105.53° and 28.84 to 102.81° and 17.71, and the oxyhemoglobin concentration tested by the functional near-infrared spectroscopy. In long-term CI-FES-assisted clinical testing, the discriminability in machine learning classification between patients and healthy individuals gradually decreased from 100% to 92.5%, suggesting a remarkable recovery tendency, further substantiated by performance on the functional movement scales. The developed CI-FES system is crucial for contralateral-hemiplegic stroke recovery, paving the way for future closed-loop stimulation systems in stroke rehabilitation is anticipated.

Managing emotions in the age of political polarization: A randomized controlled trial comparing mindfulness to cognitive reappraisal

Emotional appraisals of political stimuli (e.g., videos) have been shown to drive shared neural encoding, which correspond to shared, yet divisive, interpretations of such stimuli. However, mindfulness practice may entrain a form of emotion regulation that de-automatizes social biases, possibly through alteration of such neural mechanisms. The present study combined a naturalistic neuroimaging paradigm and a randomized controlled trial to examine the effects of short-term mindfulness training (MT) (n = 35) vs structurally equivalent Cognitive Reappraisal training (CT) (n = 37) on politically-situated emotions while evaluating the mechanistic role of prefrontal cortical neural synchrony. Participants underwent functional near-infrared spectroscopy (fNIRS) recording while viewing inflammatory partisan news clips and continuously rating their momentary discrete emotions. MT participants were more likely to respond with extreme levels of anger (odds ratio = 0.12, p < .001) and disgust (odds ratio = 0.08, p < .001) relative to CT participants. Neural synchrony-based analyses suggested that participants with extreme emotion reactions exhibited greater prefrontal cortical neural synchrony, but that this pattern was less prominent in participants receiving MT relative to CT (CT > MT; channel 1 ISC = .040, p = .030).

Social pain sharing boosts interpersonal brain synchronization in female cooperation

Social pain sharing promotes cooperation, but we still don't know its neural basis. The present study employed functional near-infrared spectroscopy (fNIRS)-based hyperscanning technology to investigate whether interpersonal brain synchronization (IBS) increased between females engaging in cooperative activities after a shared experience of social pain. We utilized the Cyberball paradigm, manipulating social pain by regulating the number of catches for the participants. Dyads in the shared social pain (SP) group received passes only at the beginning of the game, whereas dyads in the control (CT) group had the same number of catches as other players. The results indicate that participants in the SP group showed significant IBS in the right superior frontal cortex (r-SFC, p < 0.05) and left middle frontal cortex (l-MFC, p < 0.05), but no channels in the CT group showed significant IBS (p > 0.05). Further analysis revealed that IBS in r-SFC was significantly higher in the SP group compared to the CT group (p < 0.05). Additionally, IBS in r-SFC was positively correlated with the level of cooperation (r = 0.66, p < 0.001). This study elucidates the neural basis of enhanced cooperation facilitated by shared social pain at the interbrain level. However, it is crucial to acknowledge that this study exclusively enrolled female participants. The generalizability of these findings across genders is yet to be confirmed.

Effects of Reward Schedule and Avatar Visibility on Joint Agency During VR Collaboration

Joint agency, a group-level sense of agency, has been studied as an essential social cognitive element while engaging in collaborative tasks. The joint agency has been actively investigated in diverse contexts (e.g., performance, reward schedules, and predictability), yet the studies were mostly conducted in traditional 2D computer environments. Since virtual reality (VR) is an emerging technology for remote collaboration, we aimed to probe the effects of traditional reward schedule factors along with novel VR features (i.e., avatar visibility) on joint agency during remote collaboration. In this study, we implemented an experiment based on a card-matching game to test the effects of the reward schedule (fair or equal) and the counterpart's avatar hand visibility (absent or present) on the sense of joint agency. The results showed that participants felt a higher sense of joint agency when the reward was distributed equally regardless of the individual performance and when the counterpart's avatar hand was present. Moreover, the effects of reward schedule and avatar hand visibility interacted, with a bigger amount of deficit for the absent avatar hand when the reward was distributed differentially according to performance. Interestingly, the sense of joint agency was strongly correlated to the level of collaborative performance, as well as to perceptions of other social cognitive factors, including cooperativeness, reward fairness, and social presence. These results contribute to the understanding of joint agency perceptions during VR collaboration and provide design guidelines for remote collaborative tasks and environments for users' optimal social experience and performance.

Cerebral Cortex Activation and Gait Performance between Healthy and Prefrail Older Adults during Cognitive and Walking Tasks

Pre-frailty is a transitional stage between health and frailty. Previous studies have demonstrated that individuals with pre-frailty experience declines in cognitive and gait performances compared with healthy individuals. However, the basic neural mechanism underlying this needs to be clarified. In this cross-sectional study, twenty-one healthy older adults and fifteen with pre-frailty underwent three conditions, including a single cognitive task (SC), single walking task (SW), and dual-task (DT), while cortical hemodynamic reactions were measured using functional near-infrared spectroscopy (fNIRS). The prefrail group (PG) showed a significantly lower activation of the left dorsolateral prefrontal cortex (L-DLPFC) than the healthy group (HG) when performing SC (p < 0.05). The PG showed a significantly lower Timed Up and Go test and step speed than the HG during SW (p < 0.05). The coefficient of variation (CV) of the step length of the PG was significantly higher than that of the HG when performing DT (p < 0.05). No significant correlation in cerebral cortex activation and gait parameters in the HG when performing SW and DT was noted (p > 0.05). Participants of the PG with a higher oxygenated area in the left anterior prefrontal cortex (L-APFC) had a lower step frequency during SW (r = -0.533, p = 0.041), and so did the following indicators of the PG during DT: L-APFC and step speed (r = -0.557, p = 0.031); right anterior prefrontal cortex and step speed (r = -0.610, p = 0.016); left motor cortex and step speed (r = -0.674, p = 0.006); step frequency (r = -0.656, p = 0.008); and step length (r = -0.535, p = 0.040). The negative correlations between the cerebral cortex and gait parameters of the PG indicated a neural compensatory effect of pre-frailty. Therefore, older adults with pre-frailty promote prefrontal activation to compensate for the impaired sensorimotor systems.

Virtual (Zoom) Interactions Alter Conversational Behavior and Interbrain Coherence

A growing number of social interactions are taking place virtually on videoconferencing platforms. Here, we explore potential effects of virtual interactions on observed behavior, subjective experience, and neural "single-brain" and "interbrain" activity via functional near-infrared spectroscopy neuroimaging. We scanned a total of 36 human dyads (72 participants, 36 males, 36 females) who engaged in three naturalistic tasks (i.e., problem-solving, creative-innovation, socio-emotional task) in either an in-person or virtual (Zoom) condition. We also coded cooperative behavior from audio recordings. We observed reduced conversational turn-taking behavior during the virtual condition. Given that conversational turn-taking was associated with other metrics of positive social interaction (e.g., subjective cooperation and task performance), this measure may be an indicator of prosocial interaction. In addition, we observed altered patterns of averaged and dynamic interbrain coherence in virtual interactions. Interbrain coherence patterns that were characteristic of the virtual condition were associated with reduced conversational turn-taking. These insights can inform the design and engineering of the next generation of videoconferencing technology.SIGNIFICANCE STATEMENT Videoconferencing has become an integral part of our lives. Whether this technology impacts behavior and neurobiology is not well understood. We explored potential effects of virtual interaction on social behavior, brain activity, and interbrain coupling. We found that virtual interactions were characterized by patterns of interbrain coupling that were negatively implicated in cooperation. Our findings are consistent with the perspective that videoconferencing technology adversely affects individuals and dyads during social interaction. As virtual interactions become even more necessary, improving the design of videoconferencing technology will be crucial for supporting effective communication.