Social Neuroscience最新文献

Social hierarchy is a key determinant of behavior and individuals interact with others based on their social rank. Previous research has emphasized the role of the mPFC in learning social hierarchies. This study employed a social rank learning task alongside a modified version of the Ultimatum Game (UG) to investigate how individuals respond to monetary offers from different social ranks and whether the mPFC modulates these reactions. Our findings indicate that unfair offers are more likely to be rejected and offers made by individuals of lower social rank are more likely to be rejected compared to those from higher social rank. Additionally, men tend to respond quicker than women in the UG. Remarkably, participants who received tDCS over the mPFC demonstrated higher rejection rates and faster response times for offers of low-rank individuals, while the lower rejection rates and slower responses to offers from high-rank opponents. These results shed light on the neural mechanisms involved in social decision-making in competitive contexts. In particular, they reveal increased sensitivity of the mPFC to social ranks after electrical stimulation, which might be an evidence for its role in shaping decisions and reactions toward unfairness within the existing social hierarchies.

Social behavior is affected by social structure type, but how neural function changes with social type remains unclear. We investigated whether social group size affects social behaviors based on dopamine (DA) and serotonin (5-HT) systems. Four-week-old male mice were housed under different social group sizes: one, two, four, and eight mice per cage (1mpc, 2mpc, 4mpc, 8mpc, respectively). After 4 weeks, social preference, social interaction, and forced swim tests were performed to test sociability and anxiety, respectively, followed by analysis of DA and 5-HT and their metabolites (3,4-dihydroxyphenylacetic acid [DOPAC], 3-methoxytyramine [3-MT], norepinephrine, and 5-hydroxyindoleacetic acid [5-HIAA]). Social interactions and anxious behavior decreased with increased social group size. DA, 3-MT, and 5-HT levels decreased with increasing social group size, whereas DOPAC and 5-HIAA levels increased in the extended mesocorticolimbic system, including the dorsal striatum. Moreover, the increased social group size resulted in increased DOPAC/DA and 5-HIAA/5-HT ratios, accompanied by a decrease in the 3-MT/DA ratio within the extended mesocorticolimbic system. Linear regression analysis also revealed that social group size affects DA and 5-HT turnover. These suggest that social group size may influence behavior and monoamine levels, potentially contributing to DA- and 5-HT-related psychiatric disorders.

Despite its importance for daily social interactions, few studies have explored interindividual differences in the Theory of Mind (ToM) abilities of healthy adults. We used Children's False-Attribution (CFA), Children's False-Beliefs (CFB), and Belief-Desire Reasoning tasks, along with fMRI-based assessments, in a comparative analysis of ToM among primary school teachers (PST; n = 27), skilled in social interactions with children, and matched controls (MC; n = 24), who lacked such experience. PST demonstrated slower reaction times than MC in Adult and Child false-belief stories of CFB. However, no other behavioral differences between the groups and between-group differences were observed at the brain level. Both groups presented similar valence ratings for stories in the CFA. Notably, fMRI analysis revealed a group-by-condition interaction effect in the right lateral orbitofrontal cortex (OFC). In PSTs, OFC activation decreased during negative false-attribution stories regarding children compared to stories related to adults, whereas MC demonstrated an opposite activation pattern. Between-group differences in right lateral OFC activity possibly signify a neural efficiency effect secondary to frequent social interactions of PSTs, unlike the MCs, with children in the working environment. These results underscore the significance of everyday social experiences in the functional plasticity of ToM networks.

Several studies showed a positive effect of stories on Theory of Mind (ToM) performance. The aim of the present exploratory study was to investigate whether and how a specific aspect of narrative, i.e., character perspective, modulates the brain activation in response to a ToM task and improve the accuracy. Fifty participants were divided in three groups based on the text assigned: first-person perspective group (1 G; n = 16), third-person perspective group (3 G; n = 18) and a scientific essay group (EG; n = 16). The electroencephalographic and behavioral responses to eyes expressions, taken from the "Reading the Mind in the Eyes" test, were recorded pre-(T0) and post-(T1) reading task. The main results showed a greater N100 on left fronto-central electrodes and a greater P220-400 on right temporo-parietal electrodes in response to eye expressions at T1 compared to T0 in 3 G. A lower N220-400 was found on right fronto-central in response to eye expressions at T1 compared to T0 in 1 G and 3 G. The results suggest that, although reading first- and third-person stories modulates self-processes in a similar way, third-person stories involve an early stage of processing and a more extended neural network including anterior-posterior brain sites.

Neural reactions to others' pain are usually lower when the individual is of a different ethnicity than when they are of the same ethnicity. This suggests that empathy is not only an automatic phenomenon but also a motivated one. In the present study, we tested whether one's willingness to increase or decrease empathy would correspondingly increase or decrease the neural empathic response, as measured with electroencephalography (EEG), irrespective of ethnicity. In Study 1, participants were presented with pictures displaying painful or non-painful stimulations on an individual from a similar or different ethnic group. In Study 2, the procedure was relatively similar but employed a within-subject design and was conducted in two countries: Belgium and Rwanda. Overall, EEG results showed that participants successfully increased their neural response to the pain of others, irrespective of the others' ethnicity in Study 1. However, the within-subject design used in Study 2 revealed additional nuances, as we observed that participants increased their neural pain response selectively toward ingroup individuals. Our findings indicate that observing the pain of a single person, regardless of ethnicity, can heighten one's neural reaction. Yet, when both ingroup and outgroup members are present, the neural response intensifies only for ingroup members.

The chicken game, a well-established social dilemma paradigm, is widely used to study cooperative and competitive behaviors. Strategic decision-making in this game is influenced by the outcomes of cooperative and competitive interactions, with feedback-related event-related potentials (ERPs) during the feedback phase being a primary research focus. However, it remains unclear whether specific ERP components associated with strategic decision-making are present during the response phase. This study implemented a computerized chicken game featuring two cars - one representing the participant and the other the opponent - driving toward each other. Players chose to "give way" or "go straight," with the opponent's decisions controlled by a computer under high-cooperation (70% "give way") and low-cooperation (30% "give way") conditions. Participants made their choices via key presses, and outcomes were presented during the feedback phase. Results revealed a readiness potential (RP) during the response phase, with increased RP amplitudes observed when participants could not accurately predict the opponent's choice, regardless of cooperation condition. These findings suggest that the RP component reflects strategic adjustments and decision-making processes in social dilemmas, providing a potential ERP marker for such contexts.

This hyperscanning study explored the electrophysiological (EEG) patterns of dyads during a naturalistic persuasive interaction, in which the persuader had to convince the receiver that choosing a group solution was the most effective way to solve a group hypothetical everyday situation. Fifteen dyads composed of a persuader and a receiver were involved in a persuasive interaction while EEG data were recorded. EEG frequency bands (delta, theta, alpha, beta and gamma bands) were analyzed, first, considering the distinct role of the participants and, second, dividing the dyads according to the perceived effectiveness of persuasion. The intra-brain results showed greater activation of the delta, theta and alpha bands in the frontal area of the persuader compared to the receiver. The inter-brain analyses reported a significantly increased dissimilarity activation for delta and theta band in the frontal area compared to more temporo-central and parieto-occipital regions, regardless of the perceived effectiveness of persuasion. To summarize, the process of enhancing groupness during a persuasive interaction generates in the persuader a specific EEG pattern involving mainly low frequency bands activation in the frontal brain regions, suggesting a significant attentional effort and emotional involvement.

Social attention, an important mechanism that orients people to social cues, is critical for the development of higher-ordered features of social cognition. Both endogenous (i.e. automatic and undirected) and exogenous (i.e. purposeful and directed) social attention is important for processing social features, yet there is limited work systematically addressing how different experimental manipulations modulate social attention. This study examined how endogenous and exogenous manipulations of a classic face inversion task influence ERP activity in adults (n = 71) and adolescent youth (n = 65). Results from Study 1 indicated a lack of task differences for P1 and N170 but a larger inversion effect for P3 when a social perceptual decision was required. Study 2 demonstrated developmental differences in the youth, such that youth and adults had opposite inversion effects for N170 and youth had no effect for the P3. These findings indicate that face perception neural markers are sensitive to exogenous decisions, with development still active in adolescence. This is important to consider when designing future studies, as task-based decisions may alter the neural responses to faces differentially by age.

The dissolving of social bonds is disruptive and leads to increased stress responsivity and a strong desire for reunion. The oxytocin (OXT) system is critical for the formation of social attachments, such as pair bonds, and is also involved in social recognition, social memory, and social vigilance. Therefore, long-term changes in the OXT system resulting from cohabitation and pair bonding may contribute to reunion-seeking behavior. Here, we employed social conditioned place preference (SCPP) and the forced swim test (FST) to examine sensitivity to partner-associated contexts and passive stress coping following a period of partner separation. We found that opposite-sex cohabitation led to SCPP formation only in male prairie voles with a strong preference for their partner, and this SCPP was maintained following short-term loss of a pair bonded partner. Furthermore, pair bonded males that were separated from their partner displayed more passive stress-coping than those that were not bonded to their lost partner, suggesting that differences in prairie vole mating tactics (i.e. formation of a bond or not) influence the behavioral response to partner separation. Finally, we found changes in OXTR binding that may reflect variation in loss-related behavioral phenotypes based on different mating strategies.

This study investigated the impact of social isolation in Carioca High-Conditioned Freezing (CHF) rats, an animal model of generalized anxiety disorder (GAD). Animals selected for high (CHF), low trait anxiety (Carioca Low-Conditioned Freezing, CLF), and control rats from randomly bred populations (CTL) were housed in groups or kept isolated in their cages for 14 consecutive days. On the fifteenth day, all animals underwent the Forced Swimming Test (FST), where the latency to immobility was assessed as a depressive-like measure. Under standard grouping conditions, CHF rats showed a shorter latency to immobility in the FST compared to CTL and CLF animals, indicating depressive-like characteristics and possible GAD comorbidity. Social isolation decreased the latency to immobility in CLF and CTL animals, while it paradoxically increased this measure in CHF animals. Therefore, social isolation exerted a depressive-like action in CTL and CLF rats, but had a protective or "antidepressant-like" effect in CHF animals. Since, CHF rats are housed with other animals with high trait anxiety, such protective action induced by social isolation might have been due to the mitigation of what has been referred to as "social stress contagion". These results are discussed regarding the association between depressive-like behaviors and reduced social engagement.