Chapter 7: Physiological Measures of Emotion

Prefrontal Cortex

The functions of the prefrontal cortex (PFC) include planning, working memory, and inhibition of impulses. Related to emotions, the PFC is activated when people use emotional information to make decisions. For instance, people might think about how they will feel if they lie to their romantic partner (guilty!) and this prediction of the emotion guilt might help people to decide to not lie to their partner. The ventromedial prefrontal cortex (VMPFC) is a structure within the PFC. The VMPFC operates when people are anticipating how they will feel if they receive a reward (not how they will feel when they actually win the reward). The VMPFC is activated for taste, smells, touch, and social approval. When the PFC or VMPFC are damaged, people select the wrong outcomes in risky games because they cannot anticipate their emotions. Even though people understand and can verbally state the consequences of their actions, they have impaired ability to make decisions based on how they will feel after the action (e.g., sad, guilty, joyful, disappointed). Further symptoms include flat emotions, less empathy, and less reasoning about choices.

location of VMPFC in brain

Reproduced from “Cortical midlines structures” by Georg Northoff, 2013. Open Access,  Creative Commons Attribution 3.0 Unported. Retrieved from https://commons.wikimedia.org/wiki/File:Cortical_midline_structures.png 

 

Studies have linked PFC activation and damage to the occurrence of crime. Researchers (Raine et al., 1998) divided criminals into two groups – 1) people who committed impulsive, emotional murders and 2) people who committed well-thought out and premeditated murders. Impulsive murders showed greater amygdala activation and reduced PFC activation These findings might suggest that impulsive murders experienced highly intense negative emotions (due to the amygdala), but reduced inability to inhibit the amygdala’s activity and control their emotions (because of the PFC). Another study (Yang et al., 2005) compared successful and unsuccessful male psychopaths (all determined to be psychopaths from a diagnostic checklist). Successful psychopaths were males who self-reported high levels of crime, but who had not been caught for their crimes. Conversely, unsuccessful psychopaths were convicted for their criminal acts. A third group of participants represented the control group and did not meet the requirements for psychopathy. Results showed that higher psychopathy scores were linked to lower volume of prefrontal gray matter. In fact, as shown in Figure 9, unsuccessful psychopaths (compared to male controls) showed a 22.3% reduction in prefrontal gray matter. Successful psychopaths did not show a significant difference in the size of the PFC compared to the control group.

A bar chart showing relative volume of prefrontal gray matter in unsuccessful psychopaths, successful psychopaths, and the controls
The unsuccessful psychopaths showed the smallest volume of prefrontal gray matter, followed by successful psychopaths. The controls showed the biggest volume of prefrontal gray matter.

Figure 9
Volume of Hippocampus for Unsuccessful Psychopaths, Successful Psychopaths, and Control Participants

Adapted from “Volume reduction in prefrontal gray matter in unsuccessful criminal psychopaths,” by Y. Yang, A. Raine, T. Lencz, S. Bihrle, L. LaCasse, and P. Colletti, 2005, Biological Psychiatry, 57(10), p. 1106 (https://doi.org/10.1016/j.biopsych.2005.01.021). Copyright 2005 by Society of Biological Psychiatry.

 

Below is a video and an article link to the story of Charles Whitman. Charles Whitman committed the University of Texas massacre in the 1950’s. After his death, his autopsy revealed a small tumor pressing on his amygdala, thalamus, and hypothalamus. Since his autopsy, doctors have argued over the role of the tumor in his horrific actions. Did the tumor’s placement near the amygdala increase his negative emotions and aggressive behavior? Although we do not have information about the volume of his PFC, we have to wonder whether the tumor on the amygdala possibly combined with an abnormally functioning PFC could have contributed to his disastrous decision.  Watch from 4:10 to the end of the video.

 

Watch from 4:10 to the end of the video.

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Psychology 425 by Michelle Yarwood is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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