Archive for the ‘Mirror Neuron System’ Category

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

January 15, 2013

Summary

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).

More Details

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).

References

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

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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