title: Being in a Romantic Relationship Is Associated with Reduced Gray Matter Density in Striatum and Increased Subjective Happiness.
abstract: Romantic relationship, a widespread feature of human society, is one of the most influential factors in daily life. Although stimuli related to romantic love or being in a romantic relationship commonly result in enhancement of activation or functional connectivity of the reward system, including the striatum, the structure underlying romantic relationship-related regions remain unclear. Because individual experiences can alter gray matter within the adult human brain, we hypothesized that romantic relationship is associated with structural differences in the striatum related to the positive subjective experience of being in a romantic relationship. Because intimate romantic relationships contribute to perceived subjective happiness, this subjective enhancement of happiness might be accompanied by the experience of positive events related to being in a romantic relationship. To test this hypothesis and elucidate the structure involved, we compared subjective happiness, an indirect measure of the existence of positive experiences caused by being in a romantic relationship, of participants with or without romantic partners (N= 68). Furthermore, we also conducted a voxel-based morphometry study of the effects of being in a romantic relationship (N= 113). Being in a romantic relationship was associated with greater subjective happiness and reduced gray matter density within the right dorsal striatum. These results suggest that being in a romantic relationship enhances perceived subjective happiness via positive experiences. Furthermore, the observed reduction in gray matter density in the right dorsal striatum may reflect an increase in saliency of social reward within a romantic relationship. Thus, being in a romantic relationship is associated with positive experiences and a reduction of gray matter density in the right dorsal striatum, representing a modulation of social reward.
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological SciencesOkazaki, Japan; School of Medicine, Faculty of Medicine, Gunma UniversityMaebashi, Japan; Graduate School of Human Health Sciences, Tokyo Metropolitan UniversityTokyo, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kawamichi
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological Sciences Okazaki, Japan.
authors.forename: Sho K
authors.initials: SK
authors.lastname: Sugawara
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological SciencesOkazaki, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies)Hayama, Japan.
authors.forename: Yuki H
authors.initials: YH
authors.lastname: Hamano
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological Sciences Okazaki, Japan.
authors.forename: Kai
authors.initials: K
authors.lastname: Makita
authors.affiliation: Department of Health and Psychosocial Medicine, School of Medicine, Aichi Medical University Nagakute, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Matsunaga
authors.affiliation: Department of Social and Human Environment, Graduate School of Environmental Studies, Nagoya University Nagoya, Japan.
authors.forename: Hiroki C
authors.initials: HC
authors.lastname: Tanabe
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, Gunma University Maebashi, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ogino
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, Gunma University Maebashi, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological SciencesOkazaki, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies)Hayama, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sadato
keywords: gray matter density; romantic relationship; striatum; subjective happiness; voxel-based morphometry