Neural and Genetic Correlates of the Social Sharing of Happiness

Abstract

Happiness is regarded as one of the most fundamental human goals. Given recent reports that positive feelings are contagious (e.g., the presence of a happy person enhances others' happiness) because of the human ability to empathize (i.e., sharing emotions), empathic ability may be a key factor in increasing one's own subjective level of happiness. Based on previous studies indicating that a single nucleotide polymorphism in the serotonin 2A receptor gene [HTR2A rs6311 guanine (G) vs. adenine (A)] is associated with sensitivity to emotional stimuli and several mental disorders such as depression, we predicted that the polymorphism might be associated with the effect of sharing happiness. To elucidate the neural and genetic correlates of the effect of sharing happiness, we first performed functional magnetic resonance imaging (fMRI) during a “happy feelings” evocation task (emotional event imagination task), during which we manipulated the valence of the imagined event (positive, neutral, or negative), as well as the presence of a friend experiencing a positive-valence event (presence or absence). We recruited young adult women for this fMRI study because empathic ability may be higher in women than in men. Participants felt happier (p < 0.01) and the mentalizing/theory-of-mind network, which spans the medial prefrontal cortex, temporoparietal junction, temporal poles, and precuneus, was significantly more active (p < 0.05) in the presence condition than in the absence condition regardless of event valence. Moreover, participants with the GG (p < 0.01) and AG (p < 0.05) genotypes of HTR2A experienced happier feelings as well as greater activation of a part of the mentalizing/theory-of-mind network (p < 0.05) during empathy for happiness (neutral/presence condition) than those with the AA genotype. In a follow-up study with a vignette-based questionnaire conducted in a relatively large sample, male and female participants were presented with the same imagined events wherein their valence and the presence of a friend were manipulated. Results showed genetic differences in happiness-related empathy regardless of sex (p < 0.05). Findings suggest that HTR2A polymorphisms are associated with the effect of sharing happiness by modulating the activity of the mentalizing/theory-of-mind network.

Is collectivistic forgiveness different from individualistic forgiveness? Dispositional correlates of trait forgivingness in Canada and Japan.

“…The original project included a wider range of measures than reported in this study (see Ishii et al, 2018;Matsunaga et al, 2017;Matsunaga et al, 2018, for already-published outputs CULTURE AND FORGIVENESS (Supplementary Materials) 8 from this project). In the original study, participants provided for their nail samples for genetic polymorphism analyses in both Canada and Japan.…”

Association between categorization of emotionally-charged and neutral visual scenes and parameters of event-related potentials in carriers of different COMT, HTR2A, BDNF gene genotypes

“…The MRI data obtained in the work of ( Matsunaga et al , 2017 ), indicates that the polymorphisms of the HTR2A gene are associated with individual differences in the manifestation of empathy and in experiencing happiness. Brain structures responsible for providing a mental model of empathizing with other people, include the medial prefrontal cortex, as well as the temporoparietal region.…”

A Genetic Variation in the Y Chromosome Among Modern Japanese Males Related to Several Physiological and Psychological Characteristics

“…Thus, replicating the present experiment using larger samples is necessary to draw stronger conclusions. Fifth, considering the gene–gene interaction, the present study investigated the interaction between Y-DNA haplogroup D-M55 and not only DRD2 , but also other autosomal gene polymorphisms associated with BMI and human relationships, such as 5HTTLPR (Luo et al, 2016 ), rs806377 ( CNR1 ; Matsunaga et al, 2018 ), rs53576 ( OXTR ; Nishina et al, 2015 ), and rs6311 ( HTR2A ; Matsunaga et al, 2017 ). However, we did not mention these interactions in this article.…”

“…An a priori power analysis estimated the necessary sample size for this study as N = 432 (analysis of variance, fixed effects, omnibus, one-way; effect size = 0.15; alpha error = 0.05; 1-beta error = 0.80; number of groups = 3). This study used data from three sub-studies of the aforementioned research project (Matsunaga et al, 2017(Matsunaga et al, , 2018Ishii et al, 2018;Zheng et al, 2020). The first sub-study, which was conducted at Kobe University in 2015, involved 213 participants.…”

“…We used a subset of the project’s data to test for subtle effects of the haplogroup D-M55 × several autosomal gene polymorphisms on BMI and perceived number of close friends in Japanese university students. In this project, we analyzed several gene polymorphisms, such as serotonin (5-hydroxytryptamine: 5-HT) transporter gene-linked polymorphic region (5-HTTLPR) (Luo et al, 2016 ), rs806377 (cannabinoid receptor 1 gene: CNR1 , Matsunaga et al, 2018 ), rs53576 (oxytocin receptor gene: OXTR , Nishina et al, 2015 ), rs1800497 (dopamine D2 receptor gene: DRD2 , Takeuchi et al, 2015 ; Murakami et al, 2017 ), and rs6311 (5-HT (serotonin) receptor 2A gene: HTR2A , Matsunaga et al, 2017 ). We showed the results of the gene–gene interaction between haplogroups D-M55 and DRD2 using multiple regression analyses with reference to the study by Erzurumluoglu et al ( 2018 ).…”