NEURAL SYNCHRONY AND GRAY MATTER VARIATION IN HUMAN MALES AND FEMALES: AN INTEGRATION OF 40 HZ GAMMA SYNCHRONY AND MRI MEASURES

Synchrony within, synchrony without: establishing the link between interpersonal behavioural and brain-to-brain synchrony during role-play

Interpersonal synchrony is a crucial construct in understanding social interactions, which has been used in clinical studies to measure the quality of the therapeutic alliance. However, there is a lack of studies investigating the correlation between synchrony expressed on different levels: behavioural and neurophysiological. Furthermore, there are no studies that examine how the implementation of psychodramatic role-playing techniques, when individuals adopt the persona of a different character, may influence intrinsic biobehavioural synchrony between two parties. The present study, therefore, aims to uncover the relationship between behavioural and brain-to-brain synchrony across different role-playing techniques and elucidate the impact of these synchronies on participants' levels of anxiety and empathy. By using functional near-infrared imaging and behavioural coding in a dyadic role-playing paradigm (n = 41 dyads), the study found correlations between behavioural and brain-to-brain synchrony during naturalistic conversations, but not during role-play, implying a qualitative change in interpersonal synchrony when implementing role-playing techniques. Additionally, the study noted significant contributions of both behavioural and brain-to-brain synchrony as well as peripheral factors such as dyadic sex make-up and role immersion in predicting dyadic anxiety and empathy changes. Findings call for future studies to consider role-playing scenarios as a qualitatively different form of social interaction.

Culture, sex and social context influence brain-to-brain synchrony: an fNIRS hyperscanning study

BACKGROUND

Unique interpersonal synchrony occurs during every social interaction, and is shaped by characteristics of participating individuals in these social contexts. Additionally, depending on context demands, interpersonal synchrony is also altered. The study therefore aims to investigate culture, sex, and social context effects simultaneously in a novel role-play paradigm. Additionally, the effect of personality traits on synchrony was investigated across cultures, and a further exploratory analysis on the effects of these variables on pre- and post-session empathy changes was conducted.

METHODS

83 dyads were recruited in two waves from Singapore and Italy and took part in a within-subjects session where they interacted with each other as themselves (Naturalistic Conversation) and as others (Role-Play and Role Reversal). Big Five Inventory (administered pre-session) and Interpersonal Reactivity Index (administered pre- and post-session) were used as measures of personality and empathy respectively, while synchrony was measured using hyperscanning functional near-infrared spectroscopy in the prefrontal cortex. After data-preprocessing and preliminary analyses, a mixture of multiple linear regression and exploratory forward stepwise regression models were used to address the above study aims.

RESULTS

Results revealed significant main and interaction effects of culture, sex and social context on brain-to-brain synchrony, particularly in the medial left cluster of the prefrontal cortex, and a unique contribution of extraversion and openness to experience to synchrony in the Italian cohort only. Finally, culture-driven differences in empathy changes were identified, where significant increases in empathy across sessions were generally only observed within the Singaporean cohort.

CONCLUSIONS

Main findings indicate lowered brain-to-brain synchrony during role-playing activities that is moderated by the dyad's sex make-up and culture, implying differential processing of social interactions that is also influenced by individuals' background factors. Findings align with current literature that role-playing is a cognitively demanding activity requiring greater levels of self-regulation and suppression of self-related cognition as opposed to interpersonal co-regulation characterized by synchrony. However, the current pattern of results would be better supported by future studies investigating multimodal synchronies and corroboration.

Function-structure associations of the brain: evidence from multimodal connectivity and covariance studies

Despite significant advances in multimodal imaging techniques and analysis approaches, unimodal studies are still the predominant way to investigate brain changes or group differences, including structural magnetic resonance imaging (sMRI), functional MRI (fMRI), diffusion tensor imaging (DTI) and electroencephalography (EEG). Multimodal brain studies can be used to understand the complex interplay of anatomical, functional and physiological brain alterations or development, and to better comprehend the biological significance of multiple imaging measures. To examine the function-structure associations of the brain in a more comprehensive and integrated manner, we reviewed a number of multimodal studies that combined two or more functional (fMRI and/or EEG) and structural (sMRI and/or DTI) modalities. In this review paper, we specifically focused on multimodal neuroimaging studies on cognition, aging, disease and behavior. We also compared multiple analysis approaches, including univariate and multivariate methods. The possible strengths and limitations of each method are highlighted, which can guide readers when selecting a method based on a given research question. In particular, we believe that multimodal fusion approaches will shed further light on the neuronal mechanisms underlying the major structural and functional pathophysiological features of both the healthy brain (e.g. development) or the diseased brain (e.g. mental illness) and, in the latter case, may provide a more sensitive measure than unimodal imaging for disease classification, e.g. multimodal biomarkers, which potentially can be used to support clinical diagnosis based on neuroimaging techniques.

Upward spirals of positive emotions counter downward spirals of negativity: insights from the broaden-and-build theory and affective neuroscience on the treatment of emotion dysfunctions and deficits in psychopathology

This review integrates Fredrickson's broaden-and-build theory of positive emotions with advances in affective neuroscience regarding plasticity in the neural circuitry of emotions to inform the treatment of emotion deficits within psychopathology. We first present a body of research showing that positive emotions broaden cognition and behavioral repertoires, and in so doing, build durable biopsychosocial resources that support coping and flourishing mental health. Next, by explicating the processes through which momentary experiences of emotions may accrue into self-perpetuating emotional systems, the current review proposes an underlying architecture of state-trait interactions that engenders lasting affective dispositions. This theoretical framework is then used to elucidate the cognitive-emotional mechanisms underpinning three disorders of affect regulation: depression, anxiety, and schizophrenia. In turn, two mind training interventions, mindfulness and loving-kindness meditation, are highlighted as means of generating positive emotions that may counter the negative affective processes implicated in these disorders. We conclude with the proposition that positive emotions may exert a countervailing force on the dysphoric, fearful, or anhedonic states characteristic of psychopathologies typified by emotional dysfunctions.

Effects of age and sex on developmental neural networks of visual-spatial attention allocation

Compared to our understanding of the functional maturation of brain networks underlying complex cognitive abilities, hardly anything is known of the neurofunctional development of simpler cognitive abilities such as visuo-spatial attention allocation. Furthermore, nothing is known on the effect of gender on the functional development of attention allocation. This study employed event related functional magnetic resonance imaging to investigate effects of age, sex, and sex by age interactions on the brain activation of 63 males and females, between 13 to 38years, during a visual-spatial oddball task. Behaviourally, with increasing age, speed was traded for accuracy, indicative of a less impulsive performance style in older subjects. Increasing age was associated with progressively increased activation in typical areas of selective attention of lateral fronto-striatal and temporo-parietal brain regions. Sex difference analysis showed enhanced activation in right-hemispheric inferior frontal and superior temporal regions in females, and in left-hemispheric inferior temporo-parietal regions in males. Importantly, the age by sex interaction findings showed that these sex-dimorphic patterns of brain activation may be the result of underlying sex differences in the functional maturation of these brain regions, as females had sex-specific progressive age-correlations in the same right inferior fronto-striato-temporal areas, while male-specific age-correlations were in left medial temporal and parietal areas. The findings demonstrate progressive functional maturation of fronto-striato-parieto-temporal networks of the relatively simple function of attention allocation between early adolescence and mid-adulthood. They furthermore show that sex-dimorphic patterns of enhanced reliance on right inferior frontal, striatal and superior temporal regions in females and of left temporo-parietal regions in males during attention allocation may be the result of underlying sex differences in the functional maturation of these brain regions.

Sex-dependent age modulation of frontostriatal and temporo-parietal activation during cognitive control

Developmental functional imaging studies of cognitive control show progressive age-related increase in task-relevant fronto-striatal activation in male development from childhood to adulthood. Little is known, however, about how gender affects this functional development. In this study, we used event related functional magnetic resonance imaging to examine effects of sex, age, and their interaction on brain activation during attentional switching and interference inhibition, in 63 male and female adolescents and adults, aged 13 to 38. Linear age correlations were observed across all subjects in task-specific frontal, striatal and temporo-parietal activation. Gender analysis revealed increased activation in females relative to males in fronto-striatal areas during the Switch task, and laterality effects in the Simon task, with females showing increased left inferior prefrontal and temporal activation, and males showing increased right inferior prefrontal and parietal activation. Increased prefrontal activation clusters in females and increased parietal activation clusters in males furthermore overlapped with clusters that were age-correlated across the whole group, potentially reflecting more mature prefrontal brain activation patterns for females, and more mature parietal activation patterns for males. Gender by age interactions further supported this dissociation, revealing exclusive female-specific age correlations in inferior and medial prefrontal brain regions during both tasks, and exclusive male-specific age correlations in superior parietal (Switch task) and temporal regions (Simon task). These findings show increased recruitment of age-correlated prefrontal activation in females, and of age-correlated parietal activation in males, during tasks of cognitive control. Gender differences in frontal and parietal recruitment may thus be related to gender differences in the neurofunctional maturation of these brain regions.