Neural and hormonal mechanisms in aggression

Question 1

Neural Mechanisms in Aggression

Answer 1

Neural mechanisms involve brain structures and neurotransmitters that influence aggression. Key areas include the amygdala and the prefrontal cortex, which help regulate emotional responses and impulse control.

Question 2

Amygdala and Aggression

Answer 2

The amygdala is involved in processing threats and fear. Overactivation of the amygdala has been linked to heightened aggression. Dysfunctional connections between the amygdala and prefrontal cortex can impair regulation of aggressive impulses.

Question 3

Findings from Amygdalotomy and Electrical Stimulation

Answer 3

Amygdalotomy (surgical removal of part of the amygdala) has been found to reduce aggressive behaviours in individuals with uncontrollable violent tendencies. Electrical stimulation of the amygdala has been shown to trigger aggressive responses in both animals and humans.

Question 4

Serotonin and Aggression

Answer 4

Serotonin is a neurotransmitter that plays a role in mood regulation and impulse control. Low levels of serotonin are associated with increased aggression, as it impairs the brain’s ability to regulate emotional responses.

Question 5

Serotonin Turnover and Aggression

Answer 5

Serotonin turnover refers to the rate at which serotonin is produced, used, and replenished. Low serotonin turnover is linked to impulsive and aggressive behaviours.

Question 6

Higley et al. (1996) Study

Answer 6

In a study on rhesus monkeys, Higley et al. found that individuals with lower serotonin turnover exhibited more impulsive behaviours, higher rates of risk-taking, and more frequent aggressive encounters.

Question 7

Valzelli and Bernasconi (1979) Study

Answer 7

This study demonstrated that when serotonin levels were experimentally reduced in animals, they exhibited increased levels of aggressive behaviour, highlighting the role of serotonin in aggression control.

Question 8

Tryptophan and Aggression (Moeller et al., 1996)

Answer 8

Tryptophan is an amino acid precursor to serotonin. Moeller et al. found that reducing dietary tryptophan led to decreased serotonin levels and increased aggressive behaviour in human participants, supporting the link between serotonin and aggression.

Question 9

Strengths of Serotonin-Aggression Theory

Answer 9

Supported by both human and animal research, including studies showing that dietary manipulation can affect aggression levels. Provides a biological explanation for aggressive behaviours.

Question 10

Limitations of Serotonin-Aggression Theory

Answer 10

The relationship between serotonin and aggression is complex, and findings are not always consistent. Environmental and psychological factors may interact with serotonin levels, making causation difficult to establish.

Question 11

Hormonal Mechanisms in Aggression

Answer 11

Testosterone, the primary male sex hormone, has been linked to aggressive behaviour. Higher levels of testosterone are thought to increase dominance and aggressive tendencies.

Question 12

Dabbs et al. (1987) Study

Answer 12

Dabbs found that male prisoners with higher testosterone levels were more likely to have committed violent crimes compared to those with lower testosterone levels. This suggests a link between testosterone and aggression.

Question 13

Van Goozen et al. Study

Answer 13

This study found that female-to-male transgender individuals receiving testosterone therapy reported increased levels of aggression and assertiveness, providing further evidence for the hormone’s role in influencing aggression.

Question 14

Genetic Factors in Aggression

Answer 14

Genes are thought to influence aggression by affecting brain function and neurotransmitter levels. One key gene is the MAOA gene, which regulates the metabolism of neurotransmitters like serotonin.

Question 15

MAOA Gene

Answer 15

The MAOA gene, sometimes called the ‘warrior gene,’ affects the breakdown of neurotransmitters such as serotonin. Certain variants of this gene have been linked to increased aggressive behaviour.

Question 16

Brunner et al. (1993) Findings

Answer 16

Brunner et al. studied a Dutch family with a history of violent behaviour and found that male family members had a mutation in the MAOA gene, leading to deficient MAOA production and increased aggression.

Question 17

Cases et al. (1995) Study

Answer 17

This study on genetically modified mice lacking the MAOA gene found that these mice exhibited increased aggression and heightened stress responses, supporting the role of MAOA in aggression regulation.

Question 18

Strength of the MAOA Gene Explanation

Answer 18

The Brunner et al. and Cases et al. studies provide compelling evidence for a genetic basis of aggression, demonstrating how genetic mutations can influence behaviour.

Question 19

Christiansen (1977) Study

Answer 19

Christiansen conducted a twin study on 3586 pairs of twins and found higher concordance rates for aggressive behaviour in monozygotic (MZ) male twins (35%) compared to dizygotic (DZ) male twins, (12%) suggesting a genetic component to aggression.

Question 20

Evaluation of Christiansen (1977) Study

Answer 20

Strength: Provides evidence for a genetic influence on aggression through twin comparisons. Weakness: Environmental factors were not adequately controlled, making it difficult to isolate genetic influences.

Question 21

Strengths of Genetic Explanations

Answer 21

Supported by evidence from twin studies, family studies, and animal research. Provides insight into how genetics may predispose individuals to aggressive behaviour.

Question 22

Weaknesses of Genetic Explanations

Answer 22

Fails to account for environmental and situational factors. Cannot fully explain why some individuals with genetic predispositions do not exhibit aggressive behaviour.