Ruixue Luo

A functional polymorphism of the OXTR gene is associated with autistic traits in Caucasian and Asian populations

There is increasing evidence for associations between polymorphisms of the oxytocin receptor (OXTR) gene and autism spectrum disorder, but to date no study has established links with autistic traits in healthy subjects and potential cultural differences. The present research firstly investigated associations between three widely studied OXTR SNPs and autistic and empathic traits (rs53576 (G/A); rs2254298 (G/A); rs2268498 (T/C)) in two independent studies on male and female Caucasian (n = 537) and Chinese students (n = 280). Autistic and empathic traits were measured in all subjects in the two independent groups using the Autism ‐Spectrum Quotient (AQ) and the Interpersonal Reactivity Index (IRI) respectively, together with their sub‐scales. For both sites, genotyping of the OXTR SNPs was conducted on buccal swab samples using a Cobas Z 480 Light Cycler following automated DNA extraction. Associations at the genotype level with autism trait scores were found in Caucasian subjects for rs2268498 only, with TT carriers having the lowest AQ scores compared with those carrying at least one C‐allele. This finding was independently replicated in the Chinese sample although a smaller proportion carried the C‐allele compared with the Caucasian sample. Some minor associations were found between empathy trait scores and the three SNPs but were not consistent between the samples. These findings show for the first time that the rs2268498 SNP localized in the promoter flanking region of the OXTR gene is associated with autistic traits in different ethnic/cultural groups. This provides further support for the role of the OXTR gene in relation to autism.

Oxytocin biases men but not women to restore social connections with individuals who socially exclude them

We normally react to individuals who exclude us socially by either avoiding them or increasing our attempts to interact with them. The neuropeptide oxytocin can promote social bonds and reduce social conflict and we therefore investigated whether it facilitates more positive social responses towards individuals who exclude or include us. In a double-blind, placebo-controlled, between-subject design 77 healthy Chinese male and female participants received intranasal oxytocin (40 IU) or placebo before playing a modified virtual ball-tossing game with three fictitious partners who either showed exclusion, inclusion or neutral behavioral interactions with them. Results showed that both male and female subjects threw the ball more often to individuals who excluded rather than included them, although oxytocin did not alter this or awareness/feelings of exclusion or inclusion. However, when subjects returned a week later males, but not females, in the oxytocin group exhibited an increased liking for, and preference for playing again with, players who had previously excluded them. This oxytocin effect was positively associated with independent traits. Our findings suggest that in a collectivist culture oxytocin may promote the desire of males, but not females, with a stronger independent orientation to rebuild social connections with individuals who have previously excluded them.

The Role of Empathy and Life Satisfaction in Internet and Smartphone Use Disorder

Recent studies have yielded initial evidence for an association between Internet Use Disorder (IUD), empathy, and life satisfaction. In the present study we sought to replicate these previous findings, and then to extend this research by also examining the relationship between empathy, life satisfaction, and the related phenomenon of Smartphone Use Disorder (SUD). The present study included independent samples from China (N = 612, 162 females) and Germany (N = 304, 207 females), with the same set of questionnaires administered to both samples. IUD was measured with Pawlikowskis s-IAT and SUD was assessed with the short version of Kwons Smartphone Addiction Scale. The Interpersonal Reactivity Index (IRI) was used to assess individual differences in empathy. Please note that for the German sample data on the empathy quotient (EQ) are also available. Life satisfaction data were collected using items from the SOEP-Questionnaire (Socio-Economic Panel, Germany). In both of our samples we replicated previous findings showing the association between higher IUD, lower empathy, and lower life satisfaction scores. In addition, individuals with higher SUD showed higher scores on the IRI Personal Distress scale in China and Germany, while further associations between IRI dimensions and SUD were only found in the Chinese sample. Personal Distress is known to be highly correlated with the personality trait of Neuroticism, hence higher stress/negative emotionality in tense social situations is related to SUD. In the present study we confirm earlier findings showing the relationship between empathy, life satisfaction, and IUD, and extend some of these findings to SUD. We also emphasize the importance of cross-cultural studies when investigating IUD/SUD in the context of empathy and life satisfaction.

Sex- and context-dependent effects of oxytocin on social sharing

&NA; We interact socially and form bonds with others because such experiences are rewarding. However, an insecure attachment style or social anxiety can reduce these rewarding effects. The neuropeptide oxytocin (OXT) may facilitate social interactions either by increasing their rewarding experience or by attenuating anxiety, although effects can be sex‐ and attachment‐style dependent. In this study, 128 pairs of same‐sex friends completed a social sharing paradigm in a double‐blind, placebo‐controlled, between‐subject design with one friend inside an MRI scanner and the other in a remote behavioral testing room. In this way we could examine whether intranasal‐OXT differentially modulated the emotional impact of social sharing and associated neural processing. Additionally, we investigated if OXT effects were modulated by sex and attachment style. Results showed that in women, but not men, OXT increased ratings for sharing stimuli with their friend but not with a stranger, particularly in the friend in the scanner. Corresponding neuroimaging results showed that OXT decreased both amygdala and insula activity as well as their functional connectivity in women when they shared with friends but had the opposite effect in men. On the other hand, OXT did not enhance responses in brain reward circuitry. In the PLC treated group amygdala responses in women when they shared pictures with their friend were positively associated with attachment anxiety and OXT uncoupled this. Our findings demonstrate that OXT facilitates the impact of sharing positive experiences with others in women, but not men, and that this is associated with differential effects on the amygdala and insula and their functional connections. Furthermore, OXT particularly reduced increased amygdala responses during sharing in individuals with higher attachment anxiety. Thus, OXT effects in this context may be due more to reduced anxiety when sharing with a friend than to enhanced social reward.

Oxytocin facilitation of acceptance of social advice is dependent upon the perceived trustworthiness of individual advisors

The neuropeptide oxytocin may increase social cohesion by making us more willing to trust others and/or to conform to their opinions. Here we investigated whether intranasal oxytocin can influence acceptance of advice given on solving everyday social problems by either individual expert (psychologist) or non-expert advisors with or without influencing their perceived likeability or trustworthiness. In a double-blind, between-subject, placebo-control design study in 160 male and female subjects, intranasal oxytocin (24IU) only significantly enhanced acceptance of advice given by female psychologists who were rated as the most trustworthy advisors. However, oxytocin itself did not alter either trustworthiness or likeability ratings. The oxytocin effect on acceptance of the female psychologists advice was not maintained after a week, with subjects mainly reverting to their original solutions. These findings suggest that while oxytocin can transiently increase acceptance of advice from the most trustworthy individuals this is because it makes subjects more likely to conform to their opinions rather than enhancing their perceived trustworthiness or likeability. Thus in every day contexts oxytocin may primarily promote social cohesion by facilitating conformity towards the opinions of the most trusted individuals.

Sex- and Context-dependent Effects of Oxytocin on Social Reward Processing

We interact socially and form bonds with others because such experiences are rewarding. However, an insecure attachment style or social anxiety can reduce these rewarding effects. The neuropeptide oxytocin (OXT) may facilitate social interactions either by increasing their rewarding experience or by attenuating anxiety, although effects can be sex- and attachment-style dependent. In this study, 64 pairs of same-sex friends completed a social sharing paradigm in a double-blind, placebo-controlled, between-subject design with one friend inside an MRI scanner and the other in a remote behavioral testing room. In this way we could examine whether intranasal-OXT differentially modulated the emotional impact of social sharing and associated neural processing. Additionally, we investigated if OXT effects were modulated by sex and attachment style. Results showed that in women, but not men, OXT increased ratings for sharing stimuli with their friend but not with a stranger, particularly in the friend in the scanner. Corresponding neuroimaging results showed that OXT decreased both amygdala and insula activity as well as their functional connectivity in women when they shared with friends but had the opposite effect in men. On the other hand, OXT did not enhance responses in brain reward circuitry. In the PLC treated group amygdala responses in women when they shared pictures with their friend were positively associated with attachment anxiety and OXT uncoupled this. Our findings demonstrate that OXT facilitates the impact of sharing positive experiences with others in women, but not men, and that this is associated with differential effects on the amygdala and insula and their functional connections. Furthermore, OXT particularly reduced increased amygdala responses during sharing in individuals with higher attachment anxiety. Thus, OXT effects in this context may be due more to reduced anxiety when sharing with a friend than to enhanced social reward.

Oxytocin promotes lying for personal gain in a genotype-dependent manner

Society values honesty, since it fosters trust in others. Although we have a strong moral aversion to lying, particularly when it is self-serving, we nevertheless lie quite frequently and the biological basis for this is poorly understood. The hypothalamic neuropeptide oxytocin has been implicated in a number of anti-social as well as pro-social behaviours, including lying to benefit in-group members or in competitive situations. The aim of the present study was to investigate the effects of oxytocin administration on self-serving lying behaviour and possible moderating effects of genetic underpinnings of the oxytocin receptor. A total of 161 adult men participated in a randomized double-blind placebo-controlled between-subject intranasal oxytocin administration (24 International Units) study where self-serving lying was assessed using the die-in-a-cup paradigm. Additionally, contributions of polymorphisms in the oxytocin receptor gene were investigated using a haplotype approach. Results showed that while placebo-treated subjects behaved honestly across three successive rounds, oxytocin administration promoted self-serving lying, particularly in the third / last round and only to a certain degree (not to the maximum). Moreover, this effect of oxytocin was strongest in carriers of the GCG individual haplotype (rs237887-rs2268491-rs2254298) and non-carriers of the GT individual haplotype (rs53576-rs2268498) on the oxytocin receptor gene. Overall our findings demonstrate that oxytocin administration can promote self-serving lying when subjects are given repeated opportunities to lie and that these effects are moderated by genetic underpinnings of the oxytocin receptor.

Oxytocin amplifies sex differences in human mate choice

Infidelity is the major cause of partnership breakups across cultures and individuals with a history of infidelity are more likely to repeat it, although they may also present a greater opportunity for short-term sexual relationships. Here we have firstly investigated sex-differences in the attractiveness and perceived relationship potential of individuals who have exhibited fidelity or infidelity in a previous relationship. We also examined whether these sex differences are amplified by the neuropeptide oxytocin which promotes partner bonds but may also enhance sex-differences in social priorities. While both sexes valued faithful individuals most for long-term relationships, men were more interested in having short-term relationships with previously unfaithful individuals than women, irrespective of current relationship status. Oxytocin administration increased men’s attraction to unfaithful women and wanting short-term relationships with them, whereas women became more averse to unfaithful men and instead exhibited an even greater preference for having long-term relationships with faithful ones. The oxytocin effect on relationship-choice was only found in single individuals in line with their higher priority for finding a prospective partner. Thus, oxytocin release during courtship may first act to amplify sex-dependent priorities in attraction and mate choice before subsequently promoting romantic bonds with preferred individuals.

The COMT Val158Met Polymorphism and Reaction to a Transgression: Findings of Genetic Associations in Both Chinese and German Samples

After a transgression, people often either tend to avoid the transgressor or seek revenge. These tendencies can be investigated via a trait approach and surprisingly little is known about their biological underpinnings. One promising candidate gene polymorphism, which may influence individual differences in avoidance of a transgressor and vengefulness, is the COMT Val158Met (rs4680) polymorphism known to affect dopaminergic signaling and among others brain activity in situations in which people punish others for their behavior. We therefore investigated the molecular genetics of individual differences in Avoidance Motivation and vengefulness with a focus on this polymorphism. Possible genetic associations were first investigated in a sample of N = 730 Chinese participants (n = 196 females) using buccal cells to extract the DNA for genotyping. To replicate the findings we carried out a parallelized investigation in a sample of N = 585 German participants (n = 399 females). Chinese and German versions of the TRIM-12 and the Vengeance Scale were implemented to assess individual differences in tendencies to react to a transgression. Results show that Met allele carriers of the COMT Val158Met polymorphism (Val/Met and Met/Met) score significantly higher on the tendency to avoid a transgressor in the Chinese male and female samples, with an especially pronounced effect in the female subgroup. The same effect could be found in the German sample, again especially in females. Additionally, carrying a Met allele was associated with higher vengefulness in the Chinese sample only, especially in males. The present findings indicate that the COMT Val158Met polymorphism might influence individual differences in the motivation to avoid transgressors across cultures, especially in females. However, its association with vengefulness seems to be more complex and may exhibit some cultural and gender specific effects.

Gait Influence Diagrams in Parkinson’s Disease

Previous studies have shown that gait patterns differ between Parkinson’s disease (PD) patients and controls. However, almost all these studies focused only on univariate time series of a single variable. This approach cannot reveal detailed information of foot loading dynamics and the cooperative relationships of different anatomical plantar foot areas when the subjects walk. By contrast, we propose a novel multivariate method for analyzing gait patterns of the PD patients: Gait Influence Diagrams (GIDs). These are constructed by analyzing the Wiener–Akaike–Granger– Schweder influences between vertical ground reaction force signals at different plantar areas of both feet. In this paper, we use the particular case of WAGS influence measures known as “extended Granger causality analysis”. GIDs are directed graphs, with arrows indicating those influences that are significantly different between PD patients and healthy subjects. We confirm prior clinical observations that Parkinsonian gait differs significantly from the healthy one in the anterior-posterior movement direction. A new finding is that there are also pathological changes in the lateral-medial direction. Importantly, gait asymmetry for the PD patients is clearly evident in GIDs, even in earlier stages of the disease. These results suggest that GID might be of use in future PD gait pattern studies.