Archive for the ‘Frontal cortex’ Category

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

February 1, 2013


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.

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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).


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


Playing music together: coordinated actions, attuned brains

January 21, 2013


The ability to coordinate our actions with someone else in real time is necessary for playing music together, dancing with others, playing sports, and a host of day-to-day social interactions.  But how do our brains mediate this social coordination?  Sänger et al (2012) begin to address this question by studying brain activity coordination in pairs of guitarists playing a duet.

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Playing musical instruments together well requires an ongoing listening and awareness of ourselves and each other, a close attunement and flexible responsiveness to each other, and a coordination of actions between people, which has been termed “interpersonal action coordination” Sänger et al (2011).  This kind of attunement and coordination is also necessary when people dance or play certain types of sports together, or engage in many other types of less formalized social interactions that require coordinated action and are important in daily life, e.g. having a conversation or carrying out a task with someone (Sänger et al 2011; Sebanz et al 2006).  How is this mental and emotional attunement and motor coordination between two people mediated by the coordinated functioning of their brains?

A recent study by Sänger et al (2012) addressed this question by measuring electrical brain activity in pairs of people playing guitar duets, and by looking for similarities in electrical activity between the two brains during the playing.  The study included 12 sets of two skilled guitarists playing together a Rondo by Christian Gottlieb Scheidler, which involves changes in tempo.  The participants played the music from memory while facing each other.  They played the piece together 60 times on one test day, and another 60 times on a second test day.  The electrical activity of each player’s brain was recorded during the testing using electroencephalography (EEG).  To maximize the possibility that similarities in brain electrical activity of the two players would be related to interpersonal action coordination, and not just to identical perception (e.g. hearing) or identical movements (guitar playing movement), the study was designed so that the two players played somewhat different parts of the music, though the authors acknowledge that the perceptions and motions of the players were still quite similar.  The study found that coherence in activity between the two brains was most pronounced at the times that put a high demand on coordination of playing, e.g. at the time of tempo setting, and that this activity coherence was found especially at the front and center of the two brains. Between-brain coherence was seen especially in slow rhythm brain waves called theta waves.

The authors infer that frontal and central areas of the brain are particularly important for interpersonal action coordination.  They argue that these data support their model that this type of real-time coordination of action requires brain representation of one’s own actions and the actions of one’s partners and the effects of those actions (Sänger et al 2011).  They point out that brain research on interpersonal action coordination is only beginning, and much more research is needed to clarify the particular brain circuits involved, because the methods used in this study do not localize the source of the brain activity very precisely.  In addition, to studying how between-brain coherence works in those skilled it coordinating their actions, it will also be important and clinically relevant to study what is different about the brain functioning of individuals who have more difficulty with activities that demand coordination of action with another individual.


Sänger J, Lindenberger U, Müller V (2011) Interactive brains, social minds.  Communicative and Integrative Biology 4(6):655-663.

Sänger J, Müller V, Lindenberger U (2012) Intra- and interbrain synchronization and network properties when playing guitar in duets.  Frontiers in Human Neuroscience 6:312.

Sebanz N, Bekkering H, Knoblich G (2006) Joint action:  bodies and minds moving together.  Trends in Cognitive Sciences 10(2):70-76.

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

Face-to-Face communication: neurobiology of a vanishing art?

January 15, 2013


Emails, texts, social media—electronic communications are amazingly efficient, but what we gain in speed and efficiency seems to come at a cost.  What do we sacrifice by having more and more communication through our computers and smart phones, and less and less face-to-face communication? Is there something distinctive on a neurobiological level about face-to-face communication relative to other types of communication?  A recent article by Jiang et al (2012) suggests that there is.  The authors point out that face-to-face communication is the most “multi-modal,” i.e. involves integrating the most and richest types of social sensory information, allowing us to hear the tone of voice and see the facial expression and body language of the person we’re communicating with in real time.  Also, face-to-face communication involves a continuous pacing of turn taking in the conversation, which is often lost in electronic communications.  Jiang et al (2012) find that a specific area of the brain—the left inferior frontal cortex, which is an important location of mirror neurons—undergoes synchronized activity in pairs of people specifically during back-and-forth, face-to-face communication, and not in other types of in-person communication (e.g. back-to-back communication or monologues).

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The authors used a method called functional near-infrared spectroscopy (fNIRS)-based hyperscanning to measure the brain activity simultaneously in sets of two people involved in face-to-face conversations.  For more information on fNIRS, see Irani et al (2007) and Ferrari and Quaresima (2012).  The research participants were young adults in the Beijing, China area–10 same-sex pairs that already were acquainted with each other–that had conversations during scanning.  Each pair engaged in 5 different tasks while their brains were scanned:  resting state (eyes closed, relaxed mind, motionless—as baseline condition), face-to-face dialog, face-to-face monologue, back-to-back dialog, and back-to-back monologue.  The dialogs were about current news topics.  Participants were allowed to use spontaneous gestures and facial expressions during dialog.  The study found an increase in neural synchronization (synchronized brain activity levels in each member of the pair) in the left inferior frontal cortex (IFC) specifically during face-to-face dialog, but not in the other conditions.  Thus, the neural synchronization in the left IFC occurred in the pair not only when they could see and hear each other’s social cues, but also when they engaged in turn taking (a dialog rather than a monologue).  The left IFC is a hub of the mirror neuron system.  The authors conclude that face-to-face communication is distinctive, in part, because it activates neural circuits differently from other types of communication.  For more on the subject of neural synchronization during social interactions, and the notion of “brain-to-brain coupling,” including the role of this  phenomenon in social behavior development and language development, see a recent review by Hasson et al (2012).


Ferrari M, Quaresima V (2012) A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application.  Neuroimage 63(2):921-935.

Hasson U, Ghazanfar AA, Galantucci B, Garrod S, Keysers C (2012) Brain-to-brain coupling:  a mechanism for creating and sharing a social world.  Trends Cogn Sci 16(2):114-121.

Irani F, Platek SM, Bunce S, Ruocco AC, Chute D (2007) Functional near infrared spectroscopy (fNIRS):  an emerging neuroimaging technology with important applications for the study of brain disorders.  Clin Neuropsychol 21(1):9-37.

Jiang J, Dai B, Peng D, Zhu C, Liu L, Lu C (2012) Neural synchronization during face-to-face communication.  Journal of Neuroscience 32(45):16064-16069.

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

Social networks, social brain

November 9, 2012


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.

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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.


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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