Neural and Hormonal Mechanisms Flashcards
What are the two neural influences in aggression?
- The limbic system
- Serotonin
What is the limbic system?
A system of subcortical structures in the brain associated with regulating emotional behaviour
Which key structures make up the limbic system?
- Amygdala
- Hippocampus
- Hypothalamus
What is the amygdala?
Evaluates emotional importance of sensory information in the environment and prompting an appropriate response
How is the amygdala implicated in aggression?
Increased reactivity of amygdala= higher aggression
What is serotonin?
A neurotransmitter that has inhibitory, calming effects in the brain
How is serotonin implicated in aggression?
Reduced levels= removal of inhibitory effect leading to more impulsive and aggressive behaviour
What is a key hormonal influence in aggression?
Testosterone
What is testosterone?
A hormone produced mainly by males associated with development of male secondary sexual characteristics, but also implicated in aggression
What was the study that explored the influence of the amygdala on aggression?
Gospic at al. (2011)- he gave ptpts a range of scenarios in a game. Their brains where fMRI scanned and when ptpts rejected the unfair offer (aggressive reaction) scans showed highlighted response by the amygdala.
When ptpts were given a benzodiazepine which reduces the autonomic system they found two effects:
1. the number of rejections halved
2. reduced activity of the amygdala
What was the study that explored the influence of serotonin on aggression?
Mann et al. (1990)- he gave 35 healthy ptpts dexfenfluramine, an appetite suppressant which decreased serotonin levels. He found the drug treatment in mass was associated with an increase in hostility and aggression scores in a questionnaire
What was the two studies that explored the influence of testosterone on aggression?
Dolan et al. (2001)- found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 uk offenders
Dabbs et al. (1987)- measured salivation testosterone in violent and non-violent offenders. Those with the highest levels of testosterone had a history of primarily violent crimes compared to the lower levels with non-violent crimes
What is the 2 Strengths of Neural aggression mechanisms?
Effects of drugs on serotonin- Research found that drugs that increase serotonin levels decrease aggressive behaviour. German teal.(2009) gave ptpts either a placebo or a drug enhancing serotonin activity. When ptpts played a laboratory based game involving electric shocks the drugged ptpts gave fewer and less intense shocks than the placebo ptpts.
Influence of serotonin on animals- Raleigh metal. (1991) used vervet monkeys that had been fed diets of high tryptophan which increases serotonin levels. The diet change resulted in decreased levels of aggression compared to monkeys on low tryptophan diets who showed increased aggressive behaviour.
Counter- It is difficult to generalise from animals to humans as humans are more complex.
What is the strength of hormonal aggression mechanisms
Supporting evidence- Dolan et al. (2001) and Dabbs et al. (1987) provide evidence for the role of hormones play in aggressive responses.
Counter- Both of these studies and majority of other N and H influences on aggression tend to be correlational. it is important which variable is the cause of the other or if a third variable is the cause of the other or if a third variable is involved.
What is the limitation of neural aggression mechanisms?
Role of brain structures- studies revealed that the amygdala does not operate in isolation in determining aggression. it functions in tandem with the orbitofrontal Cortex (OFC), which is not part of the limbic system. Coccaro et al. (2007) found that patients with psychiatric disorders who showed aggression had reduced activity in the OFC disrupting its impulsive control function and leading to increased aggression. Suggest the regulation of aggression is complex and involves more than just one singular structure.
