The interacting brain: Dynamic functional connectivity among canonical brain networks dissociates cooperative from competitive social interactions

Shared genetics and causal relationship between sociability and the brain's default mode network

BACKGROUND

The brain's default mode network (DMN) plays a role in social cognition, with altered DMN function being associated with social impairments across various neuropsychiatric disorders. However, the genetic basis linking sociability with DMN function remains underexplored. This study aimed to elucidate the shared genetics and causal relationship between sociability and DMN-related resting-state functional MRI (rs-fMRI) traits.

METHODS

We conducted a comprehensive genomic analysis using large-scale genome-wide association study (GWAS) summary statistics for sociability and 31 activity and 64 connectivity DMN-related rs-fMRI traits (N = 34,691-342,461). We performed global and local genetic correlations analyses and bi-directional Mendelian randomization (MR) to assess shared and causal effects. We prioritized genes influencing both sociability and rs-fMRI traits by combining expression quantitative trait loci MR analyses, the CELLECT framework - integrating single-nucleus RNA sequencing (snRNA-seq) data with GWAS - and network propagation within a protein-protein interaction network.

RESULTS

Significant local genetic correlations were identified between sociability and two rs-fMRI traits, one representing spontaneous activity within the temporal cortex, the other representing connectivity between the cingulate and angular/temporal cortices. MR analyses suggested potential causal effects of sociability on 12 rs-fMRI traits. Seventeen genes were highly prioritized, with LINGO1, ELAVL2, and CTNND1 emerging as top candidates. Among these, DRD2 was also identified, serving as a robust internal validation of our approach.

CONCLUSIONS

By combining genomic and transcriptomic data, our gene prioritization strategy may serve as a blueprint for future studies. Our findings can guide further research into the biological mechanisms underlying sociability and its role in the development, prognosis, and treatment of neuropsychiatric disorders.

Transcriptomic and glucose metabolism of connectome dynamics variability in temporal lobe epilepsy revealed by simultaneous PET-fMRI

Temporal lobe epilepsy (TLE) is associated to genetic predisposition, metabolic abnormalities, and disruptions in brain connectivity. However, the relationships between genetic factors, metabolic processes, and brain network dynamics are not yet fully understood. Simultaneous positron emission tomography and function magnetic resonance imaging (PET/fMRI) data were collected from 66 patients with TLE and 38 healthy controls (HCs). We compared differences in brain network dynamics between TLE patients and HCs using the multilayer network model constructed from extensive temporal features extracted from fMRI. Postmortem whole brain gene expression data were then utilized to identify genes associated with alterations in TLE connectome dynamics, with subsequent enrichment analysis for functional annotation, cellular, and disease associations. Mediation analysis further explored the interrelations among gene expression, glucose metabolism as measured by PET, and brain network dynamics as measured by fMRI. Compared with HCs, individuals with TLE exhibited increased module variability primarily in the default mode network and reduced module variability in the attention network. These case-control differences were validated through split-half analyses and remained unaffected by medication or lateralization. These aberrant module variability patterns were associated with gene expression profiles predominantly related to inhibitory neurons, postsynaptic cell components, MAPK signaling pathway, and these genes were significantly enriched relative to established epilepsy-related gene sets. Moreover, we observed that the effect of gene expression profile on the alterations in TLE connectome dynamics was significantly mediated by changes in glucose metabolism. These findings highlight that alterations in brain network dynamics in TLE are associated with transcriptomic signatures, and that glucose metabolic changes partially mediate this relationship, furthering insights into the biological basis of the disorder.

Altered Patterns of Dynamic Functional Connectivity Underpin Reduced Expressions of Social-Emotional Reciprocity in Autistic Adults

To identify the neurocognitive mechanisms underpinning the social difficulties that characterize autism, we performed functional magnetic resonance imaging on pairs of autistic and non-autistic adults simultaneously whilst they interacted with one another on the iterated Ultimatum Game (iUG)-an interactive task that emulates the reciprocal characteristic of naturalistic interpersonal exchanges. Two age-matched sets of male-male dyads were investigated: 16 comprised an autistic Responder and a non-autistic Proposer, and 19 comprised non-autistic pairs of Responder and Proposer. Players' round-by-round behavior on the iUG was modeled as reciprocal choices, and dynamic functional connectivity (dFC) was measured to identify the neural mechanisms underpinning reciprocal behaviors. Behavioral expressions of reciprocity were significantly reduced in autistic compared with non-autistic Responders, yet no such differences were observed between the non-autistic Proposers in either set of dyads. Furthermore, we identified latent dFC states with temporal properties associated with reciprocity. Autistic interactants spent less time in brain states characterized by dynamic inter-network integration and segregation among the Default Mode Network and cognitive control networks, suggesting that their reduced expressions of social-emotional reciprocity reflect less efficient reconfigurations among brain networks supporting flexible cognition and behavior. These findings advance our mechanistic understanding of the social difficulties characterizing autism.

Deeper affection, more consumptions: consumer decision-making among people with different levels of intimacy-evidence from fNIRS

Consumer decision-making varies according to an individual's relationship with the recipient of the gift. This study used a mock purchase task to investigate consumer decision-making and its underlying neurological mechanisms when purchasing gifts of different prices for recipients with varying levels of intimacy. Functional near-infrared spectroscopy was used to record neural activity during the task. Behavioral results found that the lover group had a much higher purchasing rate than the friend group, particularly when acquiring premium products. Analysis of the functional near-infrared spectroscopy data found that neural activity in the dorsolateral prefrontal cortex and orbitofrontal cortex decreased when items were discounted, with lower activation in the dorsolateral prefrontal cortex in lovers during the purchasing of premium products. Furthermore, we identified significant differences in functional connectivity between the dorsolateral prefrontal cortex and orbitofrontal cortex under different conditions. We compared the support vector machine algorithm and logistic regression, finding that logistic regression better predicts purchasing tendencies based on neuroactivation levels. In our view, a stronger emotional connection leads to a more rewarding experience for consumers when buying premium products. This study reveals the impact of intimate relationships on consumer decision-making and provides guidance for businesses in developing marketing strategies targeted at the lover's market.

Intimate relationships regulate female brain activity in a competitive context: evidence from EEG and functional connectivity analysis

Competition is common in life, and intimate relationships are essential. Understanding how intimate relationships impact an individual's competitive process is crucial. This study explored the impact of competitor gender on female competition using electroencephalography analysis. The results revealed that females exhibited a smaller median of the absolute value of reaction time difference (DRT) between their partners and their competitors when their partners were absent compared to when their partners were present. Additionally, females showed greater average amplitudes of N2 posterior contralateral component (N2pc) and Late Positive Potential (LPP), increased activation of the alpha frequency band, and enhanced theta frequency band functional connectivity between the central parietal lobe and occipital lobe. Furthermore, when competing with individuals of the same gender as opposed to individuals of the opposite gender, females exhibited greater average amplitudes of percentage of wins and N2pc. A significant negative correlation was noted between the DRT and the average wave amplitudes of N2pc and LPP. These findings suggest that females are more engaged in competitive tasks when partners are not present and have improved decision-making when competing with same-gender individuals. This study provides evidence for the influence of lovers on female competition, helping females adapt to social competition and promoting healthy relationships.

Favoritism or bias? Cooperation and competition under different intergroup relationships: evidence from EEG hyperscanning

Cooperation and competition are the most common forms of social interaction in various social relationships. Intergroup relationships have been posited to influence individuals' interpersonal interactions significantly. Using electroencephalography hyperscanning, this study aimed to establish whether intergroup relationships influence interpersonal cooperation and competition and the underlying neural mechanisms. According to the results, the in-group Coop-index is better than the out-group, whereas the out-group Comp-index is stronger than the in-group. The in-group functional connectivity between the frontal-central region and the right temporoparietal junction in the β band was stronger in competition than cooperation. The out-group functional connectivity between the frontal-central region and the left temporoparietal junction in the α band was stronger in cooperation than competition. In both cooperation and competition, the in-group exhibited higher interbrain synchronization between the prefrontal cortex and parietal region in the θ band, as well as between the frontal-central region and frontal-central region in the α band, compared to the out-group. The intrabrain phase-locking value in both the α and β bands can effectively predict performance in competition tasks. Interbrain phase-locking value in both the α and θ bands can be effectively predicted in a performance cooperation task. This study offers neuroscientific evidence for in-group favoritism and out-group bias at an interpersonal level.

Intimate Relationships Weaken Female Competition: Evidence from Phase-amplitude Coupling and Event-Related Potentials

Competition, an essential component of social interaction, frequently occurs in daily life, and the impact of intimate relationships on women's competition has not yet been revealed. In this study, the visual target paradigm was used to explore the neural mechanisms underlying the regulation of female competitiveness by intimate relationships using event-related potential (ERP) data, time-frequency analysis, and brain functional connectivity. The research results indicate that, the P1, the N4, and the LPP were sensitive to the impact of intimate relationships on competition. Compared to competition between unfamiliar opposite-gender dyads, the average amplitudes of the N4 and LPP were higher in the late stage of competition between romantic partners. Compared to competition with strangers of the opposite gender, alpha band power was significantly higher when female individuals competed with their romantic partners. In addition, there was a positive correlation between the synchronization of activity in the frontal, parietal, and right temporal lobes of a female's brain and their degree of female engagement in competition. When a female individuals focused on the competition, activity synchronization was higher. The results indicate that competition with unfamiliar individuals of the opposite gender can make female focus on the competitive task, causing synchronous activation of corresponding brain regions. When competing with a romantic partner, women's focus decreases, their willingness to compete decreases, and the synchrony of brain functional connectivity decreases. This study suggests that intimate relationship weakens women's competitiveness, which is of significant importance for understanding high-quality intimate relationship and promoting the development of healthy competition.