Shared neural mechanisms underlying social warmth and physical warmth

Yearning for connection? Loneliness is associated with increased ventral striatum activity to close others

Loneliness is a distressing state indicating that one's basic need for social connection is not being met. In an effort to satisfy the need for social connection, loneliness may increase the processing of social cues and desire to connect with others. Yet the neural substrates that contribute to the drive for increased connection in response to loneliness are not known. The ventral striatum (VS), previously shown to increase in response to craving food and other rewarding stimuli, may contribute to "social craving" when one is lonely. That is, the VS may track one's 'hunger' for reconnection much as it tracks hunger for food. To examine this, participants reported on their feelings of loneliness before undergoing an fMRI scan where they viewed cues of potential social reconnection (images of a close other). Consistent with the hypothesis that loneliness stems from an unmet need for connection, loneliness was associated with reduced feelings of connection with the close other. Furthermore, greater reported loneliness was associated with increased VS activity to viewing a close other (vs stranger). Results extend the current literature by showing that lonely individuals show increased activity in reward-related regions to their closest loved ones, possibly reflecting an increased desire for social connection.

You did not mean it: Perceived good intentions alleviate sense of unfairness

Previous research has reported that feedback-related negativity (FRN) may represent the degree of perceived unfairness in the ultimatum game (UG). However, few studies have incorporated intention-related consideration in examining the neural correlates of fairness perception. To address this issue, the present study introduced an intentional UG paradigm to disentangle the effect of perceived intention from fairness concerns, using an event-related potential (ERP) analysis. Consistent with the hypothesis, the behavioral results indicated that good intention could markedly reduce rejection rates, and this intention effect was modulated by the degree of fairness, which was more prominent under unfair scenarios. Further electrophysiological results showed that, for the unfair division schemes, FRN and P300 amplitudes were significantly different between offers proposed with good intention and those with bad intention, while such discrepancies were not observed for the fair condition. In summary, converging results demonstrated that perceived intention can modulate the effect of fairness in social decision-making.

The Cold Heart

Mere reminders of money have been shown to cause socially “cold” behavior. Recent research suggests that the metaphor of “social coldness” is bodily grounded and thus linked to actual sensations of physical coldness. We therefore hypothesized that reminding individuals of money causes them to feel physically colder. This hypothesis was put to test in two studies, drawing on predictions from psychophysiological thermal perception. In Study 1, individuals who had been reminded of money perceived the air in the room as colder compared to a control group (an assimilation effect). Contrarily, in Study 2, they perceived water (a medium that was only momentarily experienced) as warmer compared to individuals not reminded of money (a contrast effect). Together these findings demonstrate that reminders of money cause sensations of actual physical coldness and add to the literature of both the psychological effects of money and human thermal perception.

The role of the ventral striatum in inflammatory-induced approach toward support figures

Although considerable research has shown that inflammation leads to social withdrawal more generally, it is also possible that inflammation leads to social approach when it comes to close others. Whereas it may be adaptive to withdraw from strangers when sick, it may be beneficial to seek out close others for assistance, protection, or care when sick. However, this possibility has never been explored in humans nor have the neural substrates of these behavioral changes. Based on the role of the ventral striatum (VS) in responding to: (1) the anticipation of and motivation to approach rewarding outcomes and (2) viewing social support figures, the VS may also be involved in sickness-induced approach toward support figures. Thus, the goal of the present study was to examine whether inflammation leads to a greater desire to approach support figures and greater VS activity to viewing support figures. To examine this, 63 participants received either placebo or low-dose endotoxin, which safely triggers an inflammatory response. Participants reported how much they desired to be around a self-identified support figure, and viewed pictures of that support figure while undergoing an fMRI scan to assess reward-related neural activity. In line with hypotheses, endotoxin (vs. placebo) led participants to report a greater desire to be around their support figure. In addition, endotoxin (vs. placebo) led to greater VS activity to images of support figures (vs. strangers), and greater increases in inflammation (IL-6 levels) were associated with greater increases in VS activity. Together, these results reveal a possible neural mechanism important for sickness-induced social approach and highlight the need for a more nuanced view of changes in social behavior during sickness.

Somatic influences on subjective well-being and affective disorders: the convergence of thermosensory and central serotonergic systems

Current theories suggest that the brain is the sole source of mental illness. However, affective disorders, and major depressive disorder (MDD) in particular, may be better conceptualized as brain-body disorders that involve peripheral systems as well. This perspective emphasizes the embodied, multifaceted physiology of well-being, and suggests that afferent signals from the body may contribute to cognitive and emotional states. In this review, we focus on evidence from preclinical and clinical studies suggesting that afferent thermosensory signals contribute to well-being and depression. Although thermoregulatory systems have traditionally been conceptualized as serving primarily homeostatic functions, increasing evidence suggests neural pathways responsible for regulating body temperature may be linked more closely with emotional states than previously recognized, an affective warmth hypothesis. Human studies indicate that increasing physical warmth activates brain circuits associated with cognitive and affective functions, promotes interpersonal warmth and prosocial behavior, and has antidepressant effects. Consistent with these effects, preclinical studies in rodents demonstrate that physical warmth activates brain serotonergic neurons implicated in antidepressant-like effects. Together, these studies suggest that (1) thermosensory pathways interact with brain systems that control affective function, (2) these pathways are dysregulated in affective disorders, and (3) activating warm thermosensory pathways promotes a sense of well-being and has therapeutic potential in the treatment of affective disorders.

Cold Thermal Temperature Threatens Belonging

Recent research suggests that thermal (cold vs. warm) experience influences people’s perception and construal of the social world. Extending this line of research, the present investigation examined whether cold thermal temperature would influence people’s psychological feelings of belonging. We found that drinking cold water threatened feelings of belonging (Study 1). An additional study replicated this effect and further showed that it was moderated by perceived family support, such that the effect of cold water on the belonging was only found among participants with low family support (Study 2). These findings not only strengthen the interconnection between social and physical experiences, but they also demonstrate the interactive effect of these two types of experiences on psychological feelings. Implications are discussed.

Bitter Taste Causes Hostility

The present research tested the novel hypothesis that bitter taste increases hostility. Theoretical background formed the intimate link of the taste-sensory system to the visceral system, with bitter intake typically eliciting a strong aversion response. Three experiments using differential bitter and control stimuli showed that hostile affect and behavior is increased by bitter taste experiences. Specifically, participants who consumed a bitter (vs. control) drink showed an increase in self-reported current hostility (Experiment 1), in hypothetical aggressive affect and hypothetical aggressive behavior (Experiment 2) and in actual hostile behavior assessed using a well-established method for non-physical laboratory aggression (Experiment 3). Furthermore, the effect occurred not only when participants were previously provoked (Experiments 2 and 3) but also when no provocation preceded (Experiment 1 and 3). Importantly, stimulus aversiveness and intensity did not influence the effects observed, ruling them out as explanations. Alternative interpretative frameworks and limitations are discussed.

The neural bases of feeling understood and not understood

Past research suggests that feeling understood enhances both personal and social well-being. However, little research has examined the neurobiological bases of feeling understood and not understood. We addressed these gaps by experimentally inducing felt understanding and not understanding as participants underwent functional magnetic resonance imaging. The results demonstrated that feeling understood activated neural regions previously associated with reward and social connection (i.e. ventral striatum and middle insula), while not feeling understood activated neural regions previously associated with negative affect (i.e. anterior insula). Both feeling understood and not feeling understood activated different components of the mentalizing system (feeling understood: precuneus and temporoparietal junction; not feeling understood: dorsomedial prefrontal cortex). Neural responses were associated with subsequent feelings of social connection and disconnection and were modulated by individual differences in rejection sensitivity. Thus, this study provides insight into the psychological processes underlying feeling understood (or not) and may suggest new avenues for targeted interventions that amplify the benefits of feeling understood or buffer individuals from the harmful consequences of not feeling understood.