Neural and hormonal influences Flashcards
(9 cards)
What is the limbic system?
An area in the brain that helps to coordinate behaviours that satisfy motivation and emotional urges (such as fear and aggression)
What two key structures in the limbs system are associated with aggression?
Amygdala - responsible for quickly evaluating the emotional importance of sensory information and prompting an appropriate response, if certain areas are stimulated electrically, aggression is the response
Hippocampus - involved in formation of LTMs and so allows animals to compare the conditions of a current threat with similar past experiences
What is the role of serotonin in aggression?
Serotonin exerts a calming, inhibitory effect on the neuronal firing in brain
Typically inhibits the firing of the amygdala - low levels of serotonin remove this inhibitory effect, with the consequence that individuals are less able to control impulsive and aggressive behaviour - The Serotonin Deficiency Hypothesis
What did Mann et al find in his study of serotonin?
Gave 35 healthy participants dexfenfluramine (known to deplete serotonin) - used a questionnaire to assess hostility and aggression levels - found treatment in males was associated with an increase in hostility and aggression scores
What did Sapolsky find about testosterone?
Removing the source of testosterone levels resulted in much lower levels of aggression while injections of synthetic testosterone led to a return of aggressive behaviour
Why is testosterone associated with males?
Have higher levels of testosterone
Dabbs et al - measured salivary testosterone in violent and non-violent criminals - those with the highest testosterone had had a history of primarily violent crimes
What evidence is there for the role of the serotonin deficiency hypothesis in aggression?
Duke et al - meta-analysis of 175 studies, involving 6500 participants - found a small inverse relationship between serotonin levels and aggression, anger and hostility
They found that only other-reported aggression was positively correlated to serotonin functioning
shows relationship is complex
What evidence is there for the role of the hippocampus in aggression?
Raine et al - studied. 2 groups of violent criminals: some who had faced conviction ‘unsuccessful psychopaths’ and some who had evaded the law ‘successful psychopaths’
MRI scans revealed asymmetries in the hippocampus in the ‘unsuccessful groups’ - the hippocampus in either hemisphere of the brain in these individuals differed in size, an imbalance (likely to have arisen in early brain development
This is believed to lead to information not being processed correctly, leading to inappropriate verbal and physical responses
Why is the relationship between testosterone and aggression in humans and remains unclear?
Some positive correlations have been reported between levels of testosterone and self-reported levels of aggression among prison inmates )Albert et al
On the other, no correlation was found between testosterone levels and actual violent behaviour among male inmates in prison
