Our need to experience intimate social connection, warm care, and social comfort persists throughout life: from our first to final days. Despite widespread appreciation for the importance of social connection for health and well-being, we lack a complete understanding of how we fulfill our social needs and the neurobiological pathways that link social connections with health. The research in the SHAN lab, therefore, tackles two interrelated questions: (1) what neurobiological pathways contribute to social connection with the people with whom we are closest? (2) how do social connections, or a lack thereof, affect health? We test these questions from the perspective that social needs are fundamental to our ability to thrive. Therefore, social needs may be supported by the same mechanisms that support other ‘basic’ bodily functions that also keep us functioning. Inherent in this perspective is the intimate link between the mind and body and the important role that social context can have on such links. As such, we borrow methods from pharmacology, neuroscience, and experimental social psychology to better understand the important experience of social connection.

Opioids and Social Connection: One class of neurochemicals long-theorized to be important for social connection is opioids (Inagaki, 2018, Current Direction in Psychological Science). However, the contribution of opioids to social connection has only recently been tested in humans. Using psychopharmacological methods, we were the first to show that blocking natural opioid processing via naltrexone (vs. placebo), leads to reduced feelings of social connection toward close others both in the lab and in daily reports outside of the laboratory setting (Inagaki, Irwin, & Eisenberger, 2015, Emotion; Inagaki, Ray, Irwin, Way, & Eisenberger, 2016, Social Cognitive & Affective Neuroscience). In our most recent study from this line of work we show that the effects of naltrexone extend to the brain (Inagaki, Hazlett, & Andreescu, under review). Thus, naltrexone (vs. placebo) reduces affiliation-related neural activity to close others, but, interestingly, not to strangers.

This line of work is generously supported by the Brain & Behavior Research Foundation.

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Social Warmth: Social experiences with close others are often described as warm or heart-warming. More than metaphor, experiences of social connection may have piggybacked onto the thermoregulatory systems that monitor temperature and perceptions of physical warmth. That is, social connections may be supported by the same mechanisms that keep the body at an optimally warm temperature. In support of this theory, we have shown that experiences of physical warmth (i.e., simply holding a warm therapeutic pack as compared to holding a room temperature object or a cold object) increases feelings of social connection (Inagaki & Eisenberger, 2013, Psychological Science; Inagaki et al., 2015, Emotion), and in the other direction, experiences of social connection with one’s own close others (i.e., reading loving messages from one’s own friends and family) increases feelings of warmth. Furthermore, experiences of physical and social warmth share overlapping neural activity in the ventral striatum (VS), and mid-insula (MI), two regions known to contribute to physically warm experiences and to social connection. Outside of the brain, we have shown that greater feelings of social connection are associated with warmer body temperatures (Inagaki et al., 2016, Plos ONE; Inagaki & Human, under review). 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.

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 giving support behavior and also (b) reduce social withdrawal or stress-related responding to facilitate effective care during times of need.

In support of our theoretical model, we have shown that giving support to others activates brain regions associated with maternal caregiving behavior in animals that also serve to reinforce such behavior (Inagaki & Eisenberger, 2012; Inagaki et al., 2016; Inagaki & Ross, 2018, all published in Psychosomatic Medicine). Further, we have shown that giving support to others (vs. a neutral control condition) leads to reduced sympathetic nervous system responding to a social stressor (Inagaki & Eisenberger, 2016, Psychophysiology) and is associated with reduced stress-related neural responding. Collectively, this line of research suggests that an unintended 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.