Social connection drives our daily thoughts and feelings, the conversations we have, the entertainment we consume, our plans for the future and our memories of the past. Despite widespread appreciation for the importance of social connection, scientists lack a complete understanding of how people fulfill and maintain their social connection needs and the pathways that link social connection with health.

Our research stems from the perspective that social connection is not just a psychological need, but a physical one. Using methods derived from pharmacology, neuroscience, psychophysiology, and experimental social psychology, we test bidirectional body-to-mind pathways to further understanding of our most critical social experiences – those we share with family, close friends, and other loved ones.

Opioids and Social Connection: Endogenous opioids, best known for their role in pleasure and pain, may also influence social connection with close others (Inagaki, 2018, Current Direction in Psychological Science). Using a pharmacological challenge to causally manipulate endogenous opioids, we have shown that blocking natural opioid processing  leads to reduced feelings of social connection toward close others in the lab and in daily reports collected outside of the lab (Inagaki et al., 2015; Inagaki et al., 2016, Inagaki et al., 2019a; Inagaki et al., 2019b; Ross et al., 2021). Thus, naltrexone (vs. placebo) reduced social connection-related neural activity to close others, and disrupted the link between subjective experience and the brain. Findings from this line of work are uncovering one of the basic pathways that mediate close social connections and informs a larger neurobiological model of social connection.

This line of work is generously supported by the Brain & Behavior Research Foundation and the National Institute on Drug Abuse (NIDA).

Social Warmth: Terms such as ‘warm feelings,’ ‘warm hearted,’ ‘warmly received,’ and the like abound in writings about social connection dating back to Confucius and the ancient Greeks through to modern day writing. Beyond language, our line of work on ‘social warmth’ shows that experiences of social connection share similar mechanisms as those that support thermoregulation, the process by which the body monitors and regulates its relatively warm internal temperature (Inagaki & Eisenberger, 2013; Inagaki et al., 2015; Inagaki et al., 2016; Inagaki, Hazlett, & Andreescu, 2019; Inagaki & Human, 2019; Inagaki & Ross, 2020). Together, our research on the overlap between social and physical warmth suggests another route by which we maintain our social connections and fulfill this social need is via warmth.

Brain and body at rest and Social Connection: The body is constantly working to sustain life – the heart beats, blood continues to flow to the brain, and so on. Might these moments of ‘rest’ where there is no explicit experimental manipulation or task contribute to social connection? Our newest line of work assesses the body and brain at rest as a potential contributor to social connection. Thus, resting (tonic) blood pressure (Inagaki & Gianaros, 2022; Umeda, Leutze, & Inagaki, 2021; Inagaki et al., 2018), normotensive variation in body temperature (Inagaki & Human, 2019), and connectivity of a subsystem of the brain at rest (Inagaki & Meyer, 2019; Inagaki, Brietzke, & Meyer, 2021) predict sensitivity to social connection. This line of work extends our theoretical perspective from experimental manipulations of the body (opioids; warmth) to resting, tonic body responses as potential contributors to social connection.

Giving Social Support: A number of theoretical perspectives highlight the importance of giving to and caring for others for continued relationship maintenance, intimacy, and health. Even so, most research on social support has focused on the benefits of receiving support; largely ignoring effects that come from the support we give to others on the individual giving. My theoretical perspective suggests that the neurobiological mechanisms that originally supported the care of infants extend to other forms of support-giving and ultimately, lead to health (Inagaki, 2018, Annals of the NY Academy of Sciences; Inagaki & Orehek, 2017 Current Directions in Psychological Science). From this perspective, caring for others is not just the “right thing to do” but is critical to our species’ survival. We have proposed that mechanisms are therefore in place to (a) reinforce and motivate support-giving behavior and (b) reduce social withdrawal or stress-related responding to facilitate effective care during times of need. Collectively, this line of research suggests that a benefit of giving may be reducing the giver’s own stress and highlights support-giving as an overlooked contributor to how social support can benefit health.

This line of work is generously supported by the National Science Foundation.