16 April 2012. A Nature Neuroscience special issue review, which appeared online April 15, highlights the field of social neuroscience, touching on issues ranging from empathy to neuroplasticity to social norms. Of special interest to SRF readers, Andreas Meyer-Lindenberg and Heike Tost, of the University of Heidelberg in Mannheim, Germany, discuss the neural mechanisms underlying social risk factors for psychiatric illnesses in a perspective article.
Social risk for mental and physical disorders
In the first piece of the series, Meyer-Lindenberg and Tost detail the evidence implicating social factors such as urban upbringing and migration in risk for schizophrenia (see SRF related news story), and outline recent neuroimaging studies implicating anterior cingulate and medial prefrontal cortex circuitry in that risk. Of course, environmental risk factors alone aren’t the culprit, and the authors also describe a role for variants in genes such as calcium channel subunit CACNA1C in social behaviors like emotion regulation. In fact, a schizophrenia risk variant in CACNA1C has been linked to altered anterior cingulate cortex activity and social behavioral deficits (Erk et al., 2010), suggesting that social environmental risk factors may interact with genetic risk variants to alter brain function.
In addition to influencing risk for schizophrenia, social impairments are a hallmark feature of the illness, and also one of the best predictors of long-term functional outcome (Penn et al., 2008). In the words of the authors, “everyday social interactions are both actor and stage for mental illness.”
One’s social environment doesn’t singularly affect mental health—physical health can be regulated by social relationships, too. In another perspective article, University of California, Los Angeles, researchers Naomi Eisenberger and Steve Cole examine the neural mechanisms underlying this link between social environment and somatic health. The authors suggest that the same threat/harm circuitry that reacts when survival is at risk is activated in adverse social situations, resulting in similar health effects. Conversely, the safety/reward circuitry that responds to pro-survival situations is also activated in positive social environments. As noted by Eisenberger and Cole, “social connections reach deep into the body to regulate some of our most fundamentally internal molecular processes.”
Although there is a strong case linking adverse social factors with worse health, the social brain is also a plastic one, and a review article by Richard Davidson of the University of Wisconsin, Madison, and Bruce McEwen of New York’s Rockefeller University provides hope for future interventions. The researchers describe how both chronic and acute social stressors can affect brain plasticity, inducing changes in dendritic spines of the amygdala, hippocampus, and prefrontal cortex. Recent studies have described beneficial effects of pro-social interventions such as meditation on both brain function and behavior, suggesting that training on such practices may lead to improved social outcomes.
A mixed bag of other social neuroscience topics
A fourth piece in the series, a perspective article authored by Jamil Zaki of Harvard University and Kevin Ochsner of Columbia University in New York, features a critical discussion of the current state of neural mechanisms underlying empathy. The authors detail the progress in the field, namely, the identification of empathy subsystems, and also describe the limitations of research on empathy. They end on a hopeful note, praising recent trends of using more naturalistic social cognitive paradigms, the development of stronger links between neural correlates and behavior, and the use of a wide range of methodologies.
Another perspective piece authored by Cade McCall and Tania Singer of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, describes how animal and human research has educated neuroendocrinological hypotheses of social behaviors. McCall and Singer review findings implicating several major neuropeptides and steroid hormones in processes such as affiliation and aggression. Next, they detail how animal research can spawn new directions in human neuroendocrinology research, and conclude with recommendations for future human studies.
In the final piece of the special issue, Joshua Buckholtz of Harvard University and René Marois of Vanderbilt University, Nashville, Tennessee, provide a commentary on the neural underpinnings of social norms, a construct that underlies the collective collaboration, or “ultra-sociality,” of human culture. The authors describe potential mechanisms underlying the acquisition and enforcement of social norms, arguing that they seem to be mediated by simple cognitive processes such as value learning rather than more complicated cognitive constructs. Implicated brain regions include the amygdala and various subregions of the prefrontal cortex.—Allison A. Curley.
Buckholtz JW and Marois R. The roots of modern justice: cognitive and neural foundations of social norms and their enforcement. Nat Neurosci. 2012. Abstract
Davidson RJ and McEwen BS. Social influences on neuroplasticity: stress and interventions to promote well-being. Nat Neurosci. 2012. Abstract
Eisenberger NI and Cole SW. Social neuroscience and health: neurophysiological mechanisms linking social ties with physical health. Nat Neurosci. 2012. Abstract
McCall C and Singer T. The animal and human neuroendocrinology of social cognition, motivation, and behavior. Nat Neurosci. 2012. Abstract
Meyer-Lindenberg A and Tost H. Neural mechanisms of social risk for psychiatric disorders. Nat Neurosci. 2012. Abstract
Zaki J and Ochsner K. The neuroscience of empathy: progress, pitfalls and promise. Nat Neurosci. 2012. Abstract