Archive for the ‘Social Reward’ 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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Contagious desires

June 20, 2012

Summary

Have you ever noticed that other people around you influence what you find desirable?  Why are we so susceptible to this kind of social influence?  An article by Lebreton and coworkers identifies brain circuits involved in our tendency to want what other people want.  This tendency and the underlying brain circuits may be important in helping us learn from others during our childhoods.

More details

Have you ever noticed that other people around you influence what you find desirable?   Maybe there is some kind of food, other item, or even person that didn’t seem to be too interesting to you until others started ooo-ing and ahh-ing over them.  Why are we so susceptible to this kind of social influence?  This desire contagion seems to be a deep-seated human tendency, and one that is very adaptive during our early development, because we learn a lot from our parents or caretakers from an early age what is desirable and safe, vs. what should be avoided.  But how does the brain mediate this social contagion of desire?  An article by Lebreton and coworkers (The Journal of Neuroscience, May 23, 2012 issue) addresses this question of what brain circuits are involved in the “mimetic desire phenomenon” or “goal contagion.”  The study recruited healthy, young adult (20-39-year-old) subjects who watched videos of people (but not including the faces of the people) reaching for one of two identical objects of different colors.  This was followed by tasks in which the subjects were asked how much they would like to use or acquire either of the identical objects of different color.  During the tasks, some subjects underwent functional magnetic resonance imaging (fMRI).

As expected, the study found that objects that had been sought by the person in the video were more likely to be desired by the subjects.   According to the authors, the fMRI data indicated that mimetic desire was mediated by an interaction between the “mirror neuron system” (parietal lobe and premotor cortex) and the “brain valuation system,” i.e. the brain reward system (ventral striatum and ventromedial prefrontal cortex).  Based on their analysis, the authors argued the mirror neuron system acted on the brain valuation system.

By design, the videos of people reaching for the objects did not include the people’s faces, because the authors wanted to eliminate a focus on joint attention, i.e. the phenomenon that people tend to look at the same stimuli that others are looking at.  The authors argue that the mimetic desire phenomenon that they are studying is distinct from joint attention because the former (mimetic desire) has to do specifically with desire (positively-valenced motivation), whereas the latter (joint attention) could have to do with any type of attentional/motivational salience, including desire, but also novelty or threat (negatively-valenced motivation).  The authors also argue that the phenomenon they studied is distinct from empathy or emotional resonance, because the subjects could not see the face and hence the emotional state of the person reaching in the videos.  In the study, there was no correlation within the subjects between mimetic desire and empathizing or mentalizing ability as measured by other psychological tests (“empathy questionnaire” and “reading mind in the eyes” tests).

Although the authors carefully distinguish the mimetic desire phenomenon from certain processes affected in autism spectrum disorders (ASD), namely joint attention and empathy, this mimetic desire phenomenon still seems potentially relevant to ASD, because individuals with ASD tend to be less influenced by the desires of others around them.  The authors do note, at the end of their manuscript, that the interaction between the mirror neuron system and the brain valuation system interaction might represent an essential method for social learning in early childhood, before sophisticated language skills have developed.  At the end of the paper, the authors raise the hypothesis that the mirror neuron system might be functionally disconnected from the brain valuation system in individuals with ASD, resulting in their being relatively unaffected by the motivations of others.  But because this study did not involve subjects with ASD, more studies would be needed to test that hypothesis.

Reference:

Lebreton M, Kawa S, Forgeot d’Arc B, Daunizeau J, Pessiglione M (2012) Your goal is mine:  unraveling mimetic desires in the human brain. Journal of Neuroscience 32(21):7146-7157.

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


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