Inter-subject gamma oscillation synchronization as a biomarker of abnormal processing of social interaction in ADHD.

Children with attention-deficit hyperactivity disorder (ADHD) have difficulties in social interactions. Studying brain activity during social interactions is difficult with conventional artificial stimuli. This pioneering study examined the neural correlates of social perception in children with ADHD and matched controls using naturalistic stimuli. We presented 20 children with ADHD and 20 age-and-sex-matched controls with tailored movies featuring high- or low-level social interactions while recording electroencephalographic signals. Both groups exhibited synchronized gamma-band oscillations, but controls demonstrated greater inter-subject correlations. Additionally, the difference in inter-subject correlations between high- and low-interaction movies was significantly larger in controls compared to ADHD patients. Between 55 and 75 Hz comparing viewing high interaction movies with low interaction moves, controls had a significantly larger weighting in the right parietal lobe, while ADHD patients had a significantly smaller weighting in the left occipital lobe. These findings reveal distinct spatiotemporal neural signatures in social interaction processing among children with ADHD and controls using naturalistic stimuli. These neural markers offer potential for group differentiation and assessing intervention efficacy, advancing our understanding ADHD-related social interaction mechanisms.

Sex of an Observer Effects on Adults' Motor, Cognitive, and Affective Dart-Shooting Performance.

Men and women are characterized by specific physiological, cerebral and emotional characteristics, as well as by the differing nature of their gestures and behaviors. Here, we examined the effects of an observer's sex on motor, cognitive and affective behaviors during dart-shooting. We compared men and women's kinematic and affective parameters when perfoming alone or when performing in the presence of an observer of a different sex. We found a sex effect on motor and cognitive performance in interaction with participants' emotional states. We observed improved accuracy and reaction time in men compared to women, which we attributed to (a) differences in emotional sensitivities between the two sexes and (b) men's superiority on precision tasks linked to men's higher proportion of cerebral white matter. Our findings also suggested a sex difference in the social effect of an observer's sex on motor and cognitive performance. Although there was no effect on affective aspects of performance, emotional state seemed to interact strongly with this social effect.

Perceptual sensitivity to changes in interpersonal distance when observing social interactions: the effects of dyad arrangement and orientation.

In recent years, there has been growing interest in how we perceive dyadic interactions between people. It has been proposed that pairs of individuals shown upright and face-to-face recruit a form of configural processing, similar to that engaged by upright faces. This processing is thought to aid the detection and interpretation of social interactions. Dyadic arrangements shown back-to-back or upside-down are not thought to engage configural dyad processing. One of the key advantages conveyed by configural face processing is greater sensitivity to the spatial relationships between facial features when faces are viewed upright, than when viewed upside-down. If upright dyads arranged face-to-face engage similar configural processing that is not engaged by non-facing or inverted dyads, participants should therefore exhibit disproportionate sensitivity to the spatial relations between the constituent actors under these conditions. In four well-powered experiments, we find no evidence for this prediction: participants exhibited similar levels of sensitivity to changes in interpersonal distance regardless of whether dyads were shown upright or inverted, face-to-face or back-to-back. In contrast, we observe clear evidence that upright presentation affords greater sensitivity to inter-feature spatial relationships (interocular distance) when viewing faces. These results suggest that any configural processing engaged by upright facing dyads likely differs qualitatively from that engaged by upright faces.

The impact of exercise on depression: how moving makes your brain and body feel better.

PURPOSE: This study aimed to comprehensively explore and elucidate the intricate relationship between exercise and depression, and focused on the physiological mechanisms by which exercise influences the brain and body to alleviate depression symptoms. By accumulating the current research findings and neurobiological insights, this study aimed to provide a deeper understanding of the therapeutic potential of exercise in the management and treatment of depression. METHODS: We conducted a systematic review of the scientific literature by selecting relevant studies published up to October 2023. The search included randomized controlled trials, observational studies, and review articles. Keywords such as "exercise," "depression," "neurobiology," "endocrinology," and "physiological mechanisms" were used to identify pertinent sources. RESULTS: Inflammation has been linked to depression and exercise has been shown to modulate the immune system. Regular exercise can (1) reduce the levels of pro-inflammatory cytokines, potentially alleviating depressive symptoms associated with inflammation; (2) help in regulating circadian rhythms that are often disrupted in individuals with depression; and (3) improve sleep patterns, thus regulating mood and energy levels. CONCLUSION: The mechanisms by which exercise reduces depression levels are multifaceted and include both physiological and psychological factors. Exercise can increase the production of endorphins, which are neurotransmitters associated with a positive mood and feelings of well-being. Exercise improves sleep, reduces stress and anxiety, and enhances self-esteem and social support. The implications of exercise as a treatment for depression are significant because depression is a common and debilitating mental health condition. Exercise is a low-cost, accessible, and effective treatment option that can be implemented in various settings such as primary care, mental health clinics, and community-based programs. Exercise can also be used as an adjunctive treatment along with medication and psychotherapy, which can enhance treatment outcomes.

Measuring information alignment in hyperscanning research with representational analyses: moving beyond interbrain synchrony.

Hyperscanning, which enables the recording of brain activity from multiple individuals simultaneously, has been increasingly used to investigate the neuropsychological processes underpinning social interaction. Previous hyperscanning research has primarily focused on interbrain synchrony, demonstrating an enhanced alignment of brain waves across individuals during social interaction. However, using EEG hyperscanning simulations, we here show that interbrain synchrony has low sensitivity to information alignment across people. Surprisingly, interbrain synchrony remains largely unchanged despite manipulating whether two individuals are seeing same or different things at the same time. Furthermore, we show that hyperscanning recordings do contain indices of interpersonal information alignment and that they can be captured using representational analyses. These findings highlight major limitations of current hyperscanning research and offer a promising alternative for investigating interactive minds.

Repeated postnatal sevoflurane exposure impairs social recognition in mice by disrupting GABAergic neuronal activity and development in hippocampus.

BACKGROUND: Repeated exposure to sevoflurane during early developmental stages is a risk factor for social behavioural disorders, but the underlying neuropathological mechanisms remain unclear. As the hippocampal cornu ammonis area 2 subregion (CA2) is a critical centre for social cognitive functions, we hypothesised that sevoflurane exposure can lead to social behavioural disorders by disrupting neuronal activity in the CA2. METHODS: Neonatal mice were anaesthetised with sevoflurane 3 vol% for 2 h on postnatal day (PND) 6, 8, and 10. Bulk RNA sequencing of CA2 tissue was conducted on PND 12. Social cognitive function was assessed by behavioural experiments, and in vivo CA2 neuronal activity was recorded by multi-channel electrodes on PND 60-65. RESULTS: Repeated postnatal exposure to sevoflurane impaired social novelty recognition in adulthood. It also caused a decrease in the synchronisation of neuronal spiking, gamma oscillation power, and spike phase-locking between GABAergic spiking and gamma oscillations in the CA2 during social interaction. After sevoflurane exposure, we observed a reduction in the density and dendritic complexity of CA2 GABAergic neurones, and decreased expression of transcription factors critical for GABAergic neuronal development after. CONCLUSIONS: Repeated postnatal exposure to sevoflurane disturbed the development of CA2 GABAergic neurones through downregulation of essential transcription factors. This resulted in impaired electrophysiological function in adult GABAergic neurones, leading to social recognition deficits. These findings reveal a potential electrophysiological mechanism underlying the long-term social recognition deficits induced by sevoflurane and highlight the crucial role of CA2 GABAergic neurones in social interactions.

Supportive care of female hormones in brain health: what and how?

Female hormones, functioning as neuroactive steroids, are utilized beyond menopausal hormone therapy. The rapid onset of allopregnanolone analogs, such as brexanolone and zuranolone, in treating depression, and the effectiveness of megestrol acetate in addressing appetite and weight gain, prompted the Food and Drug Administration to authorize the use of progesterone for treating postpartum depression and cancer-related cachexia. Progesterone has also been found to alleviate neuropathic pain in animal studies. These off-label applications offer a promising option for patients with advanced cancer who often experience various mood disorders such as depression, persistent pain, social isolation, and physical complications like cachexia. These patients have shown low tolerance to opioids and mood-regulating medications. However, the potential risks and uncertainties associated with hormone therapy treatment modalities can be daunting for both patients and medical professionals. This review aims to offer a comprehensive understanding of the non-reproductive functions and mechanisms of female hormones in brain health.

Fostering Social Interaction Between Hearing Impaired and Hearing Children: The Validation of Design and Interaction Strategies Through a Peer Interaction Game.

Objective: Hearing impaired (HI) children face challenges in establishing and maintaining relationships with their hearing (H) peers, leading to potential damages on their psychological well-being. The objective of this study is to introduce and validate design strategies and interaction strategies aimed at promoting social interaction between HI children and their H peers. Materials and Methods: With a specific focus on addressing the unique needs of HI children, the design strategies and interaction strategies were derived from the previous studies. To assess the effectiveness, these strategies were implemented in a game specifically designed to encourage peer interaction between HI and H children. Participants, including both HI and H children, were invited to experience the game and provide feedback. Results: The results demonstrated the efficacy of these strategies in fostering the social interaction between HI and H children. Participants exhibited increased engagement and cooperation during gameplay, indicating the successful facilitation of peer interactions. Conclusions: By validating design and interaction strategies through a specially designed peer interaction game, the research demonstrates the effectiveness of these strategies. The findings underscore the significance of tailored strategies that address the unique challenges faced by HI children in establishing interactions with their H peers. These validated strategies can serve as a foundation for creating inclusive environments that support the overall well-being and social integration of HI children in mainstream settings.

Cooperation and competition have same benefits but different costs.

Cooperation and competition shape everyday human interactions and impact individuals' chances of success in different domains. Using a virtual Stroop test, classically employed to assess general cognitive interference, we examined the impact of social context (cooperation and competition) and other's ability (higher and lower performers) on performance, perceived stress, and autonomic activity. In Experiment 1, we found that both cooperation with a lower performer and competition with a higher performer led to similar enhancement in performance. However, only competition with a more skilled opponent induced an increase in perceived stress and physiological activity. Experiment 2 further demonstrated that these effects persisted even with prolonged exposure to these contexts. In summary, cooperation can be just as effective as competition in improving individuals' performance. However, cooperation does not carry the same level of stress and physiological burden as the competitive context, representing a healthier and more optimal way to boost individual performance.

Positive correlation between working memory and face-to-face social interaction in everyday life.

Working memory (WM) plays a crucial role in various cognitive tasks from language comprehension to problem-solving. However, its influence on social activities has remained largely unexplored. The current two studies on individual differences, a pilot (N = 329) and a pre-registered direct replication (N = 338) study, investigated the relationship between WM and outside-the-lab social interaction by using a listening span task and three social network questionnaires (e.g., how many people a participant had contacted in the past month). The consistent patterns in the two studies were (a) WM recall was positively correlated with social network size, (b) WM recall remained positively correlated with social network size even when accounting for online interactions on WhatsApp and Facebook, and (c) WM recall was positively correlated with social network size by face-to-face interaction. These novel findings would suggest connections between WM and face-to-face social interaction. It was, however, acknowledged that the obtained effect sizes were small, and that further investigation is indeed necessary. In light of this, we also clarify future directions for understanding the relationship between WM and social interaction.

Maintaining a Dynamic Brain: A Review of Empirical Findings Describing the Roles of Exercise, Learning, and Environmental Enrichment in Neuroplasticity from 2017-2023.

Brain plasticity, also termed neuroplasticity, refers to the brain's life-long ability to reorganize itself in response to various changes in the environment, experiences, and learning. The brain is a dynamic organ capable of responding to stimulating or depriving environments, activities, and circumstances from changes in gene expression, release of neurotransmitters and neurotrophic factors, to cellular reorganization and reprogrammed functional connectivity. The rate of neuroplastic alteration varies across the lifespan, creating further challenges for understanding and manipulating these processes to benefit motor control, learning, memory, and neural remodeling after injury. Neuroplasticity-related research spans several decades, and hundreds of reviews have been written and published since its inception. Here we present an overview of the empirical papers published between 2017 and 2023 that address the unique effects of exercise, plasticity-stimulating activities, and the depriving effect of social isolation on brain plasticity and behavior.

Investigating the impact of schizophrenia traits on attention: the role of the theta band in a modified Posner cueing paradigm.

Joint attention is an indispensable tool for daily communication. Abnormalities in joint attention may be a key reason underlying social impairment in schizophrenia spectrum disorders. In this study, we aimed to explore the attentional orientation mechanism related to schizotypal traits in a social situation. Here, we employed a Posner cueing paradigm with social attentional cues. Subjects needed to detect the location of a target that is cued by gaze and head orientation. The power in the theta frequency band was used to examine the attentional process in the schizophrenia spectrum. There were four main findings. First, a significant association was found between schizotypal traits and attention orientation in response to invalid gaze cues. Second, individuals with schizotypal traits exhibited significant activation of neural oscillations and synchrony in the theta band, which correlated with their schizotypal tendencies. Third, neural oscillations and synchrony demonstrated a synergistic effect during social tasks, particularly when processing gaze cues. Finally, the relationship between schizotypal traits and attention orientation was mediated by neural oscillations and synchrony in the theta frequency band. These findings deepen our understanding of the impact of theta activity in schizotypal traits on joint attention and offer new insights for future intervention strategies.

The Impact of COVID-19 Health Measures on Adults With Multiple Chemical Sensitivity: Cross-Sectional Study.

BACKGROUND: Multiple chemical sensitivity (MCS) develops in response to repeated small-level chemical exposures or a major exposure in a subset of people, who then experience symptoms that can range from mild to debilitating when exposed to chemicals. The arrival of the COVID-19 pandemic and the stringent health measures put in place may have increased the burden for those living with MCS, as it became more challenging to avoid chemicals that trigger their condition. OBJECTIVE: This study aimed to better understand the lived experience of Canadians living with MCS during the first year of the COVID-19 pandemic. METHODS: An online questionnaire was created to ask participants to compare daily living during the pandemic to before March 11, 2020. Data were collected in January and February 2021. Three areas were investigated: (1) environmental exposures to chemical triggers from ambient air (pollution from industry, farming, and traffic) and indoor air (the smell of cleaning products, cooking odors, and smoke); (2) access to, and satisfaction with, health care visits; and (3) how people experiencing MCS rated contact with their social network. RESULTS: In all, 119 Canadians who had lived with MCS for more than a year completed the questionnaire. The participant sample was mostly female (86.6%, n=103) and highly educated, with 57.1% (n=68) having a university degree. Slightly more than half (57.1%, n=68) were older than 55 years. McNemar chi-square and Wilcoxon signed rank tests were used to evaluate if there were statistically significant changes before ("prepandemic period") and after ("postpandemic period") March 11, 2020. Perceived exposure to pollution from a highway or a road was significantly decreased from the prepandemic to postpandemic period (z=-3.347; P<.001). Analysis of industry or power plants also suggested a significant decrease in the perceived exposure from the prepandemic to postpandemic period (z=-2.152; P=.04). Participants reported an increase in exposure to odors from disinfectants or sanitizers that entered their living environment (P<.001). There was a significant decrease between prepandemic and postpandemic levels of satisfaction when attending in-person meetings with a physician (z=-2.048; P=.04), yet there were no significant differences between prepandemic and postpandemic levels of satisfaction for online or telephone meetings with a physician. Although people with MCS experienced increased social isolation (P<.001), they also reported an increase in understanding from family (P=.03) and a decrease in stigma for wearing personal protective equipment (P<.001). CONCLUSIONS: During the first year of the COVID-19 pandemic, people with MCS were impacted by inaccessibility, loss of social support, and barriers to accessing health care. This study highlights unique challenges and possible benefits associated with the COVID-19 pandemic public health measures for individuals living with MCS. These findings can guide decision makers to improve policies on accessibility through appropriate accommodation measures.

Camouflaging in Autistic Adults is Modulated by Autistic and Neurotypical Characteristics of Interaction Partners.

Many autistic people reportedly engage in camouflaging to navigate everyday social interactions; however, the function of this behavior remains largely unknown. We hypothesized that autistic people camouflage more toward neurotypical others than toward autistic others, employing it as a strategy to "fit in" within the neurotypical-majority community. This study aimed to empirically investigate this hypothesis for the first time. Autistic and neurotypical participants took part in a web-based survey. Data from 48 autistic and 137 neurotypical participants were analyzed. Camouflaging toward autistic and neurotypical others was separately measured using the modified Camouflaging Autistic Traits Questionnaire (CAT-Q). For each CAT-Q item, a sentence describing a hypothetical interaction partner with autistic or neurotypical characteristics was added, creating respective sentence conditions. The interaction effect of the participants' characteristics and sentence conditions was analyzed using a multilevel regression analysis, accounting for differing individual baselines. The analysis revealed an interaction effect between participants' characteristics and sentence conditions. The autistic group showed significantly more camouflaging in the autistic sentence condition than in the neurotypical sentence condition. Conversely, the neurotypical group did not differ significantly in camouflaging levels in the sentence conditions. Contrary to our hypothesis, autistic people demonstrated more camouflaging toward autistic others than toward neurotypical others. This finding questions the assumption that autistic people camouflage to assimilate into a neurotypical-majority society. Instead, it could be conceptualized as a more general social strategy used by autistic people aiming to improve their relationships with others.

The time course of Temporal Binding in social and nonsocial interactions.

Temporal Binding (TB) is the subjective compression of action-effect intervals. While the effects of nonsocial actions are highly predictable, it is not the case when interacting with conspecifics, who often act under their own volition, at a time of their choosing. Given the relative differences in action-effect predictability in non-social and social interactions, it is plausible that TB and its properties differ across these situations. To examine this, in two experiments, we compared the time course of TB in social and nonsocial interactions, systematically varying action-effect intervals (200-2,100 ms). Participants were told they were (a) interacting with another person via a live webcam, who was in fact a confederate (social condition), (b) interacting with pre-recorded videos (nonsocial condition), or (c) observing two pre-recorded videos (control condition; Experiment 2). Results across experiments showed greater TB for social compared to nonsocial conditions, and the difference was proportional to the action-effect intervals. Further, in Experiment 1, TB was consistently observed throughout the experiment for social interactions, whereas nonsocial TB decreased from the first to the second half of the experiment. In Experiment 2, the nonsocial condition did not differ from control, whereas the social condition did, exhibiting enhanced binding. We argue these results suggest that the sociality of an interaction modulates the 'internal clock' of time perception.

Beyond human-likeness: Socialness is more influential when attributing mental states to robots.

We sought to replicate and expand previous work showing that the more human-like a robot appears, the more willing people are to attribute mind-like capabilities and socially engage with it. Forty-two participants played games against a human, a humanoid robot, a mechanoid robot, and a computer algorithm while undergoing functional neuroimaging. We confirmed that the more human-like the agent, the more participants attributed a mind to them. However, exploratory analyses revealed that the perceived socialness of an agent appeared to be as, if not more, important for mind attribution. Our findings suggest top-down knowledge cues may be equally or possibly more influential than bottom-up stimulus cues when exploring mind attribution in non-human agents. While further work is now required to test this hypothesis directly, these preliminary findings hold important implications for robotic design and to understand and test the flexibility of human social cognition when people engage with artificial agents.

Person-centredness in dementia care: an integrative review of theoretical approaches.

OBJECTIVES: This review identifies and examines theoretical approaches (components and objectives) to person-centred dementia care in order to obtain a better understanding of what is meant by the concept of person-centred dementia care. DESIGN: Following the approach of Whittemore and Knafl, an integrative literature review was conducted to answer the following questions: (1) Which theoretical approaches to person-centred dementia care have been published? (2) What are the components of the theoretical approaches to person-centred dementia care thus identified, and which objectives can be identified? DATA SOURCES: MEDLINE (via PubMed), CINAHL (via EBSCO) and PsycINFO (via EBSCO) were searched through to 26 April 2021. ELIGIBILITY CRITERIA: We included any kind of published literature that describes theoretical approaches to person-centred dementia care and that was written in German or English. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers extracted data. Data were pooled using a data extraction form developed by the Joanna Briggs Institute. A qualitative content analysis was conducted. RESULTS: The analysis revealed heterogeneous perspectives within the identified approaches to person-centred dementia care. Statements pertaining to the components and objectives could be assigned to three different subcategories (microlevel, macrolevel and application level). This analysis enabled an enhanced understanding of how person-centred dementia care is currently described and whether and how the theoretical approaches differ in terms of their orientations and their focus on the individual and/or on sociality, which allows conclusions regarding the underlying conceptual idea of personhood. CONCLUSIONS: There is a clear challenge for future research to overcome the dominance of the focus on the individual and to consider aspects of sociality to be at least equally important. This is needed in order to understand dementia as a multifaceted phenomenon that demands a differentiated consideration of theoretical notions of how to understand personhood in this context.

From physical to digital: A theoretical-methodological primer on designing hyperscanning investigations to explore remote exchanges.

As individuals increasingly engage in social interactions through digital mediums, understanding the neuroscientific underpinnings of such exchanges becomes a critical challenge and a valuable opportunity. In line with a second-person neuroscience approach, understanding the forms of interpersonal syntonisation that occur during digital interactions is pivotal for grasping the mechanisms underlying successful collaboration in virtual spaces. The hyperscanning paradigm, involving the simultaneous monitoring of the brains and bodies of multiple interacting individuals, seems to be a powerful tool for unravelling the neural correlates of interpersonal syntonisation in social exchanges. We posit that such approach can now open new windows on interacting brains' responses even to digitally-conveyed social cues, offering insights into how social information is processed in the absence of traditional face-to-face settings. Yet, such paradigm shift raises challenging methodological questions, which should be answered properly to conduct significant and informative hyperscanning investigations. Here, we provide an introduction to core methodological issues dedicated to novices approaching the design of hyperscanning investigations of remote exchanges in natural settings, focusing on the selection of neuroscientific devices, synchronization of data streams, and data analysis approaches. Finally, a methodological checklist for devising robust hyperscanning studies on digital interactions is presented.

How is momentary well-being and stress associated in persons with spinal cord injury and their romantic partners? A study protocol for a dyadic everyday life study.

INTRODUCTION: Very little is known about daily life dynamics and mutual influences that tie together well-being and psychobiological stress responses in persons with spinal cord injury (SCI) and their romantic partners in particular. The role of social support and physical activity in the associations between emotional well-being and stress has not been investigated in the context of SCI yet and studies applying a dyadic approach, exploring the role of a romantic partner, are currently unavailable. The overall objective is thus to better understand the interplay between emotional well-being and the psychobiological stress marker cortisol, and to investigate the potentially moderating role of social support and physical activity in the well-being-stress association among persons with SCI and their romantic partners using a dyadic perspective. METHODS AND ANALYSIS: The stRess and Health Among romantic couPles with Spinal cOrD injurY study, funded by the Swiss National Science Foundation (10001C_204739), aims to recruit N=150 community-dwelling persons with SCI and their romantic partners including three phases of data collection. The first phase includes a baseline questionnaire. The second phase, the time sampling phase, comprises an ecological momentary assessment design in the everyday life of couples where both partners provide concurrent salivary cortisol samples five times a day and complete assessments four times a day over seven consecutive days. Wrist-worn accelerometers record physical activity during this period. The third phase is an observational study in the laboratory, where a couples' discussion on the SCI management in their everyday life is recorded and coded to identify a couple-specific coping with SCI to enrich data. The dyadic data will be analysed using multilevel modelling, based on the actor-partner interdependence model framework. ETHICS AND DISSEMINATION: The study was approved by the ethics committee of Northwest and Central Switzerland (2022-01072) and findings will be disseminated through peer-reviewed publications and conference presentations.

Neural correlates of static and dynamic social decision-making in real-time sibling interactions.

In traditional game theory tasks, social decision-making is centered on the prediction of the intentions (i.e., mentalizing) of strangers or manipulated responses. In contrast, real-life scenarios often involve familiar individuals in dynamic environments. Further research is needed to explore neural correlates of social decision-making with changes in the available information and environmental settings. This study collected fMRI hyperscanning data (N = 100, 46 same-sex pairs were analyzed) to investigate sibling pairs engaging in an iterated Chicken Game task within a competitive context, including two decision-making phases. In the static phase, participants chose between turning (cooperate) and continuing (defect) in a fixed time window. Participants could estimate the probability of different events based on their priors (previous outcomes and representation of other's intentions) and report their decision plan. The dynamic phase mirrored real-world interactions in which information is continuously changing (replicated within a virtual environment). Individuals had to simultaneously update their beliefs, monitor the actions of the other, and adjust their decisions. Our findings revealed substantial choice consistency between the two phases and evidence for shared neural correlates in mentalizing-related brain regions, including the prefrontal cortex, temporoparietal junction (TPJ), and precuneus. Specific neural correlates were associated with each phase; increased activation of areas associated with action planning and outcome evaluation were found in the static compared with the dynamic phase. Using the opposite contrast, dynamic decision-making showed higher activation in regions related to predicting and monitoring other's actions, including the anterior cingulate cortex and insula. Cooperation (turning), compared with defection (continuing), showed increased activation in mentalizing-related regions only in the static phase, while defection, relative to cooperation, exhibited higher activation in areas associated with conflict monitoring and risk processing in the dynamic phase. Men were less cooperative and had greater TPJ activation. Sibling competitive relationship did not predict competitive behavior but showed a tendency to predict brain activity during dynamic decision-making. Only individual brain activation results are included here, and no interbrain analyses are reported. These neural correlates emphasize the significance of considering varying levels of information available and environmental settings when delving into the intricacies of mentalizing during social decision-making among familiar individuals.