aggression

Question 1

describe the role of neural mechanisms in aggression (only limbic system)

Answer 1

• in brain is a network of structures called the limbic system. Identified as comprising of: cingulate gyrus, hypothalamus, amygdala and parts of the hippocampus
• most important structure said to be amygdala - has key role in humans and nonhuman animals in how organisms assess and respond to environmental threats and challenges
• reactivity of amygdala has proven to be an importsnt predictor of aggressive behaviour
• if amygdala malfunctions (e.g. tumour, lesion, abnormal development) then the levels of testosterone can be raised, making aggression more likely
• high testosterone levels can reduce activity of prefrontal cortex, which means that an emotional situation could become a heightened emotionally aggressive response

Question 2

describe the role of neural mechanisms in aggression (serotonin)

Answer 2

• serotonin is a neurotransmitter thought to inhibit aggressive behaviour
• therefore low levels are linked to aggression
• evidence supporting role of serotonin in aggression is very mixed. Researchers currently believe:
• serotonin is thought to mediate an individual’s response to a situation. Activation in the brain’s limbic system (centre of emotional response) is not controlled as much by the prefrontal cortex in individuals with low serotonin
• this essentially means that an individual who has low serotonin has less control over their emotional response and this can lead to aggression

Question 3

describe the role of hormonal mechanisms in aggression

Answer 3

• Hormonal mechanisms have been linked to aggression. Hormones are chemical messengers secreted by glands; testosterone is the main hormone that has been implicated in aggressive behavior
• testosterone is an androgen that produces male characteristics. Males produce higher levels of testosterone than females, which may be why aggression is more present in males
  STUDY:
• Dabbs conducted a study where he measured testosterone levels in saliva of 89 male prison inmates
• he believed those with higher testosterone conc were more likely to convicted of violent crimes
• almost all of those with the highest levels had been convicted of violent crimes and almost all of those with the lowest levels were convicted of non-violent crimes
• this associated aggressive behaviour with high levels of testosterone

Question 4

AO3 Neural mechanisms in aggression

Answer 4

SEROTONIN

• researchers conducted study where participants were given enhanced serotonin activity drug or placebo
• participants took part in lab-based game with electric shocks of varying intensity being given and received to provocation
• participants with serotonin drug consistently gave fewer and less intense shocks than placebo group
• study is a useful link between serotonin function and aggression that goes beyond usual correlation findings, crediting neural explanation
• Badawy (2006) suggested that the influence of serotonin on aggressive behaviour may be important in explaining the well-established relationship between alcohol and aggressive behaviour
• found that alcohol consumption caused major disturbances in metabolism of brain serotonin
• Acute alcohol intake depleted serotonin level in normal individuals, whereas in susceptible individuals, this depletion may induce aggressive behaviou
• findings suggest that low levels of serotonin in susceptible individuals can result in increased aggression, supporting this theory

LIMBIC SYSTEM

• there may be an over-reliance on limbic system as an explanation for aggressive behavior
• e.g. the orbitofrontal cortex (OFC) may also play a significant role, due to its link with the action of serotonin
• therefore, as suggested by Gospic et al, it may be more effective to focus on neural connections between the OFC and the limbic system, as opposed to looking at the two in isolation
• Raine et al. (1997) scanned brains of 41 murders and 41 controls. They found using PET scans that some had abnormalities in the way their limbic system functioned
• this suggested limbic system was involved in aggressive behaviour.
• PET scans used so data is scientific and objective. A controlled study
• however unable to establish cause and effect b/c only SOME had abnormalities in the way their limbic system functioned

Question 5

AO3 Hormonal mechanisms in aggression

Answer 5

• Dabb’s testosterone study
• problem with establishing a cause and effect relationship b/c data is correlational
• another factor could be causing aggressive behavior or it could be aggression raising testosterone levels
• this discredits findings of the study and therefore its role in explaining testosterone’s role in aggression

Question 6

Crockett’s serotonin study

Answer 6

Crockett et al.

• used non-physical situation of a game playing and moral dilemmas to observe behaviour
• some had serotonin levels reduced by manipulation of diet, others had theirs increased by being administered SSRI drug (temporary change)
• participants given restricted diet showed higher levels of retaliation against their opponent
• participants with higher levels of serotonin responded to emotional moral dilemmas with increased compassion
• results suggest serotonin in higher levels affect emotional response and regulates social decision making

Question 7

how were diets manipulated to increase serotonin levels in Crockett’s study?

Answer 7

Tryophan is a dietary source of serotonin

- tryophan is an amino acid that can be converted to serotonin (found in cheese, eggs and milk)