*** There is a transcript available for this episodes at https://www.medscape.com/viewarticle/940969

Yuan Chang Leong, PhD, spoke with Psychcast host Lorenzo Norris, MD, about his research into the neural underpinnings of right- and left-leaning individuals.

Dr. Leong is a postdoctoral scholar in cognitive neuroscience at the University of California, Berkeley. He has no disclosures.

Dr. Norris has no disclosures.

Take-home points

• Dr. Leong and colleagues looked for further evidence of “neural polarization,” which is defined as divergent brain activity based on conversative versus liberal political attitudes.
• The prefrontal cortex is the part of the frontal lobe responsible for executive and higher-order brain function that makes sense and organizes what a person is seeing, hearing, and experiencing.
• Participants were shown news clips about immigration policy and their brain activity showed differences in activity of their dorsomedial prefrontal cortex (DMPFC), which is active in interpreting narrative content. The findings suggest there is a neural basis for the way in which individuals with different political attitudes interpret political information and news.
• The research suggests that words related to threat, morality, emotions, anger, and differentiation/community drive neural polarization.

Summary

• Dr. Leong and colleagues asked participants to watch news clips about immigration policy while undergoing functional MRI with the goal of identifying the neural correlates of neural polarization, which is thought to parallel the behavioral aspects of political polarization.
• Dr. Leong and colleagues identified an association of divergence in connectivity to the DMPFC to the ventral striatum, a structure involved in reward processing and sensing the valence and tone of information. Their study, published in the Proceeding of the National Academy of Sciences, suggests that information from the ventral striatum is transmitted differently to the DMPFC between groups.
• The findings suggest that our political beliefs might influence our interpretation of other information, as the DMPFC helps humans interpret narrative content.
• Dr. Leong pointed out that this study provides evidence about why it is so difficult to bridge the partisan divide. He also discussed the psychology of social identity theory and how any categorization of people makes individuals think along the lines of in-group and out-group, and how the human drive is to protect the in-group.

References

Leong YC et al. PNAS. 2020 Oct 20. doi: 10.1073/pnas.2008530117.

McLeod S. Social identity theory. Simply Psychology. Updated 2019.

University of Texas, Austin. Ethics unwrapped. In-group/out-group (video).

Brooks M. Brain imaging reveals a neural basis for partisan politics. Medscape.com. 2020 Oct 27.

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Show notes by Jacqueline Posada, MD, associate producer of the Psychcast; assistant clinical professor in the department of psychiatry and behavioral sciences at George Washington University, Washington; and staff physician at George Washington Medical Faculty Associates, also in Washington. Dr. Posada has no conflicts of interest.

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