Archive for the ‘Social Affiliation’ Category

How desirable and pleasurable are social relationships? It depends on who you ask…

February 1, 2013

Summary

There are individual differences in how much people desire and seek out social interactions, and how comfortable people feel in getting emotionally close to others.  Are these individual differences in behavior related to differences in brain function?  Vrticka (2012) argues that reduced interest in social interaction and close relationships is associated with reduced activation of brain reward circuits in response to social stimuli.

More details

Most of us desire social interactions and take pleasure in close relationships with at least a small number of other people.  On the other hand, most of us also need some personal space and independence.  The preferred balance of interpersonal closeness vs. space varies from individual to individual.    A recent review by Vrticka (2012) addresses potential neural mechanisms underlying these individual differences.  Vrticka argues that, in each of us, there is a “‘push-pull’ mechanism between two opposing emotional neural circuits”(Vrticka (2012)—one of which mediates social approach/reward, and the other which mediates social avoidance/aversion (Porges et al 2003).  Vrticka writes that a likely candidate for the neural circuits that mediate social reward, e.g. the pleasures of positive interactions with a friend  or loved one, are the well-characterized brain reward circuits–including dopaminergic neurons that project from the ventral tegmental area (VTA) to the ventral striatum (VS, including the nucleus accumbens) and medial prefrontal cortex (mPFC), which mediate many different types of pleasurable and rewarding stimuli, including food and drugs of abuse.

To support the hypothesis that these neural circuits mediate social rewards, Vrticka cites an article by Fareri et al (2012) that finds greater activation of the VS and mPFC when money rewards were shared with a friend than when they were shared with an unfamiliar person.   In addition, Vrticka (2012) argues that individual differences in attachment style—a person’s relatively stable patterns of expectations, emotions, and behaviors in close relationships—maybe mediated by differences in the functioning of these brain reward circuits.  In a previous study, Vrticka and coworkers (2008) found that an “avoidant” attachment style—characterized by a preference for interpersonal distance and discomfort in getting too emotionally close to others—was associated with reduced activation of the VS in response to positive social feedback on performance in a game, but no alteration in VS responsiveness to nonsocial successes (winning the game).  As Vrticka (2012) points out, further studies of the functioning of these reward circuits seem warranted, not only for better understanding individuals differences in social reward, but also to better understand psychiatric and neurodevelopmental disorders characterized by reduced social interaction.  For example, there are recent reports of alterations in the function of brain reward circuitry in autism spectrum disorders (Kohls et al 2012a; Kohls 2012b).

References

Fareri DS, Niznikiewicz MA, Lee VK, Delgado MR (2012) Social network modulation of reward-related signals. The Journal of Neuroscience 32(26):9045-9052.

Kohls G, Chevallier C, Troiani V, Schultz RT (2012a) Social ‘wanting’ dysfunction in autism:  neurobiological underpinnings and treatment implications.  J Neurodev Disord 4(1):10.

Kohls G, Schulte-Rüther M, Nehrkorn B, Müller K, Fink GR, Kamp-Becker I, Herpertz-Dahlmann B, Schultz RT, Konrad K (2012b) Reward system dysfunction in autism spectrum disorders.  Soc Cogn Affect Neurosci, in press.

Porges SW (2003) Social engagement and attachment:  a phylogenetic perspective. Ann NY Acad Sci 1008(Dec):31-47.

Vrticka P (2012) Interpersonal closeness and social reward processing.  The Journal of Neuroscience 32(37):12649-12650.

Vrticka P, Andersson F, Grandjean D, Sander D, Vuilleumier P (2008) Individual attachment style modulates human amygdala and striatum activation during social appraisal.  PLoS One 3:e2868.

Vrticka P and Vuilleumier P (2012) Neuroscience of human social interactions and adult attachment style.  Front Hum Neurosci 6:212.

©2011-2013 Edward S. Brodkin.  All Rights Reserved

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Social networks, social brain

November 9, 2012

Summary

What circuits in the brain mediate our tendency to socially connect with others?    An article by Bickart et al 2012 finds that the functioning of particular brain circuits—including specific parts of the amygdala, an important hub of the “emotional”/limbic system of the brain—is related to the size and complexity of people’s social networks.

More details

What circuits in the brain mediate our tendency to socially connect with others?    Many studies have implicated brain circuits involving the amygdala and the frontal cortex in social behaviors.  Some of these studies (e.g. Bickart et al 2011) have found a positive correlation between size of social networks and size of the amygdala, an important hub of the “emotional”/limbic system of the brain.  Now a new study (Bickart et al 2012) provides more detailed information about the relationship between specific brain circuits involving subdivisions of the amygdala and size of social networks in healthy, young adult humans.  Bickart and co-workers (2012) measured size of individuals’ social networks using the Social Network Index (Cohen et al 1997).  They used fMRI to measure the size of the each person’s amygdala, and used a method called resting-state functional connectivity magnetic resonance imaging (fcMRI) to assess connectivity between amygdala sub-regions and various other brain regions.  Replicating their previous work (Bickart et al 2011), this 2012 study found a positive correlation between size of the amygdala and size of the social network.  In addition, they found that the strength of a circuit supporting social perception (ventrolateral amygdala connected to orbitofrontal cortex, fusiform gyrus, ventromedial temporal cortex, and superior temporal sulcus) and a circuit supporting social affiliation (medial amygdala connected to ventromedial prefrontal cortex, rostral anterior cingulate cortex, and nucleus accumbens, and ventromedial hypothalamus) predicted social network size.  However, social network size was not related to the strength of a circuit including the dorsal amygdala that supports social aversion.  Moreover, social network size and complexity was not related to connectivity within other networks important for social cognition that do not include the amygdala, specifically networks involved in mentalizing (dorsomedial prefrontal cotex connected to temporoparietal junction) or in mirror networks (ventral premotor cortex, posterior superior temporal sulcus, and intraparietal sulcus).  The authors note that “This dissociation underscores the value of studying the component processes that contribute to social connectedness since there are clearly important divisions of labor.  In this case, the size and complexity of a person’s social network depends more on corticolimbic circuitry that is important for affective processing (Barett and Bar, 2009), which in part evaluates the salience of signals from other people (Seeley et al., 2007), than on corticocortical networks that have more limited relevance for affective processing” (Bickart et al 2012). Importantly, the authors note that their findings do not indicate the extent to which the strength of these circuits related to social network size are “hard-wired” by genetics, or are modifiable by experience or other environmental factors.

References

Barrett LF, Bar M (2009) See it with feeling:  affective predictions during object perception.  Philos Tras R Soc Lond B Biol Sci 364:1325-1334.

Bickart KC, Hollenbeck MC, Barrett LF, Dickerson BC (2012) Intrinsic amygdala-cortical functional connectivity predicts social network size in humans.  Journal of Neuroscience 32:14729-14741.

Bickart KC, Wright CI, Dautoff RJ, Dickerson BC, Barrett LF (2011) Amygdala volume and social network size in humans.  Nature Neuroscience 14:163-164.

Cohen S, Doyle WJ, Skoner DP, Rabin BS, Gwaltney JM Jr (1997) Social ties and susceptibility to the common cold.  JAMA 277:1940-1944.

Seeley WW, Menon V, Schatzberg AF, Keller J, Gover GH, Kenna H, Reiss AL, Greicius MD (2007) Dissociable intrinsic connectivity networks for salience processing and executive control.  Journal of Neuroscience 27:2349-2356.

©2011-2013 Edward S. Brodkin.  All Rights Reserved


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