Identifying the neurobiological mechanisms underlying social connection. The first line of our research explores what makes up a pleasant social experience and why pleasant social experience might be good for us. One reason positive social experiences may feel so good is due to increases in “social warmth,” the pleasant, contented feeling that arises when we feel connected to those we love. It has been suggested that experiences of social connection have piggybacked onto the thermoregulatory systems that monitor temperature and perceptions of physical warmth, using the experience of physical warmth to signal close social bonds or experiences of social connection.  In other words, social warmth and physical warmth may share similar basic mechanisms. Indeed, we have shown that social and physical warmth share common neural and neurochemical substrates, shedding light on one way by which these types of positive social exchanges feel pleasant and have come to be so critical to survival.

As an extension of this work, we have explored the contribution of the endogenous opioid system to social bonding as a mechanism underlying the pleasant feelings stemming from affiliation. Here, we have shown that blocking natural opioid processing, with an opioid antagonist (vs. a placebo), leads to reduced feelings of connection both in the lab and in daily diary reports.  Together, this line of work elucidates the neurobiological mechanisms underlying experiences of social connection so that we can begin to understand how to help those lacking connections.

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

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Beneficial effects of giving support to others. Social relationships involve repeated interactions during which individuals receive and provide care and support. Even so, most research has focused on the benefits of receiving support; largely ignoring effects that come from the support we give to others. This program of research addresses this gap by assessing the psychological and physical effects of giving support on the individual performing the giving. But why might giving to others be beneficial? One perspective suggests that humans have an innate predilection to care, nurture, and protect others, especially during times of need. Thus a circuit of parental caregiving mechanisms that help mammals care for their own young extend to support caring for others such as friends, romantic partners, or other family members. In particular, a suite of hormones and neuropeptides (e.g. opioids, oxytocin) and neural regions where these neurochemicals have their central actions (e.g. ventral striatum (VS) and septal area (SA)) support effective caregiving whereas perturbations to any of these mechanisms severely disrupts normal care. From this perspective, caring for others is not just the “right thing to do,” but is critical to furthering the species. Mechanisms may therefore be in place to (a) help reinforce and motivate caregiving behavior, and also (b) reduce withdrawal or stress-related responding to facilitate care during times of need.

In the first demonstration of the contribution of parental caregiving neural regions to support-giving behavior, we have shown that giving support to loved ones activates reward-related neural regions that are involved in parental caregiving behavior in animals (ventral striatum, septal area). Moreover, greater activity in one of the reward-related neural regions is associated with reduced activity in a threat-related neural region, suggesting that giving support to others may reduce physiological threat responding.  Indeed, we have also shown that giving social support to others (vs. a control condition) leads to reduced sympathetic nervous system responding to a social stressor, providing the first experimental evidence that giving to others might be stress-reducing. Finally, we have shown that those who report giving more support, but not receiving support, show reduced stress-related neural activity in response to a social stressor and greater reward-related activity in response to social rewards. Collectively, this line in our program 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.

 

Understanding links between inflammation and social perception. This line of work explores how our inflammatory system, the body’s first defense against infection and a critical mediator in the link between stress and disease, affects social behavior and perceptions of the social world. Thus, we have shown that experimentally inducing an inflammatory response heightens neural threat responding to negative social cues and increases feelings of social disconnection. In addition, we have shown that inflammation (vs. placebo) leads to heightened activity in a reward-related neural region (ventral striatum) to close others (vs. strangers) and that participants report a greater desire to be around their loved one when under an inflammatory challenge. This work adds to an existing understanding of how inflammation affects social experiences and highlights the potential social consequences of diseases with a heightened inflammatory component (e.g. depression, cancer, cardiovascular disease).