19. Aggression III | Summary and Q&A

February 1, 2011
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19. Aggression III

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This video discusses the role of mirror neurons in empathy, the neurobiology of empathy, and the relationship between pain, empathy, and mirror neurons. It also explores the role of serotonin in aggression, the interaction between genetics and serotonin levels, the effects of alcohol on aggression, and the triggers for aggression such as pain, frustration, and overcrowding. The video also examines the relationship between hormones, such as testosterone, estrogen, and progesterone, and aggression, particularly in females. It concludes with a discussion on the effects of glucocorticoids and the sympathetic nervous system on aggression.

Questions & Answers

Q: What are mirror neurons and how do they contribute to empathy?

Mirror neurons are a class of neurons that get excited when an individual performs an action and when they observe someone else performing the same action. These neurons mirror the actions of others, hence their name. They were originally identified in motor parts of the cortex but have also been theorized to play a role in empathy and understanding others' actions and feelings.

Q: What is the role of mirror neurons in the anterior cingulate?

Mirror neurons in the anterior cingulate have been speculated to be involved in more abstract versions of empathy and feeling others' actions and emotions. However, this theory has not yet been demonstrated and remains an area of ongoing research.

Q: How does serotonin influence aggression?

Serotonin is a neurotransmitter that has been implicated in aggression and impulsive behavior. Studies have shown that lower levels of serotonin predict more impulsive and aggressive behavior in both animals and humans. However, it is important to note that measuring serotonin levels in humans is challenging and interpreting the findings can be complex, as serotonin is used for many functions in the brain.

Q: What is the relationship between genetics and serotonin levels in aggression?

Variants on genes related to serotonin receptors and enzymes involved in serotonin synthesis and breakdown have been studied in relation to aggression. Different variants have been associated with different levels of aggression and breakdown products. However, determining causality and separating genetic effects from environmental factors can be challenging, and the effects of these gene variants are not significant.

Q: How does alcohol influence aggression?

Alcohol is often associated with increased aggression, but research has shown that alcohol does not directly cause aggression. Instead, alcohol amplifies pre-existing social tendencies. If an individual is already aggressive, alcohol will increase their aggression. Conversely, if an individual is non-aggressive, alcohol may make them more inhibited.

Q: What are some triggers for aggression?

Aggression can be triggered by various factors such as pain, frustration, and overcrowding. Pain, in particular, can significantly increase the likelihood of aggression. Frustration, such as not receiving an expected reward, can also lead to displacement aggression. Overcrowding has been historically associated with increased aggression, although research suggests that aggression is amplified in individuals who are already aggressive.

Q: How do hormones, such as estrogen and progesterone, influence aggression in females?

Fluctuations in estrogen and progesterone levels have been associated with changes in aggression in females. During the perimenstrual period, which includes a few days before and after menstruation, women may experience increased irritability, anger, and aggression. These hormonal changes are also linked to depression and social withdrawal. Some evidence suggests that the ratio of estrogen to progesterone and the rapid drop of progesterone levels may play a role in these mood and behavioral changes.

Q: What factors contribute to the effects of hormones on aggression in females?

The effects of hormones on aggression in females are not solely determined by biology. Cultural and psychological factors can also influence mood and behavior during the perimenstrual period. Self-fulfilling prophecies, psychodynamic theories, and cultural norms around menstruation may all contribute to the observed changes in aggression and mood.

Q: How do glucocorticoids and the sympathetic nervous system relate to aggression?

Glucocorticoids, such as cortisol, and the sympathetic nervous system are involved in the stress response and can influence aggression. The amygdala, a brain region involved in aggression, is sensitive to the effects of glucocorticoids. Increased levels of glucocorticoids can prime the amygdala, making individuals more likely to exhibit aggressive behavior. Similarly, the sympathetic nervous system, which is activated during the fight-or-flight response, can contribute to aggression.

Q: What are some environmental factors that can influence aggression?

Environmental factors such as pain, frustration, and overcrowding have been shown to trigger aggression. These factors can exacerbate pre-existing aggressive tendencies in individuals. Additionally, social and cultural factors, as well as individual personality traits, can interact with these environmental triggers to influence aggressive behavior.


This video highlights the role of mirror neurons in empathy and the speculation of their involvement in understanding others' actions and emotions. It also emphasizes the complex relationship between serotonin and aggression, highlighting the challenges of measuring and interpreting serotonin levels in humans. The role of alcohol in amplifying pre-existing social tendencies rather than directly causing aggression is also discussed. Hormonal fluctuations in estrogen and progesterone, particularly during the perimenstrual period, have been linked to mood changes and aggression in females. The importance of considering cultural and psychological factors in understanding aggression is stressed. Finally, the effects of glucocorticoids and the sympathetic nervous system on aggression are discussed, emphasizing their role in the stress response. Overall, this video provides insights into the multifaceted factors that contribute to aggression.

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