Nerual and hormonal mechanisms in aggression

-Buried deep inside the brain a network of structures collectively labelled as the limbic system. The limbic sytem is linked to emotional behaviours such as as aggression.

-James Papez discovered how the amygdala is the most important structure. 

-Amygdala= in charge of how our body assesses and responds to the environments threats and challenges 

- the amygdala has proven to be important in prediticting aggressive behaviour

GOSPIC- 

-lab method of assessing aggressive behaviour called the ultimatum game.

- 2 players. the proposer offers to split money with the responder in a certain way. If they accept money is splir, if not they both get nothing.

-responders had FMRI, which highlight activity in different areas of the brain.

-When responders rejected the offer, they found a fast and heightened response by the amgdla

-BENZODIAZEPINE- drug which reduces the arousal of the autonomic nervous system, if this drug was taken before the game, the responder halved the number of aggresive rejections and reduced activity of amygdla.

This shows strong association with aggresion and amygdla

- recent studies have suggested that it is wrong to think that the amygdla operates on its own to determin aggression

-researchers have discovered how it functions with the OFC, which is not part of the limbic system

OFC is involved in= self control, impulse regulation and inhibition of aggresive behaviour

Coccaro= found that in patients with psychriatric problems, found that the aggresive ones had a reduced amount of OFC, which distrupts the impulse control function and creates aggression.

= neurotransmitter involved in communication between neurons.

-slows down and dampens neural activity. 

-normal levels of serotonin are linked to the obitofrontal cortext which are linked to reduced firing of neuron, associated with greater self control. 

- so unnormal levels of serotonin can be linked to lack of self control and linked to aggresive behavioue.

VIRKKUNEN- compared levels of serotonins breakdown product metabolite in spinal fluid of violent impulsive and non impulsive offenders. 

-they found levels were significantly lower in impulsive offenders and they also suffered more sleep inregularities..

This supports the role of serotonin in aggresive behaviour

-drugs that increase serotonin also reduce levels of aggressive behaviour

-Berman gave particips placebo or paroxetine which enhances serotonin

- lab experiment involved in giving electric shocks in response to provocation

-paroxetine gave fewer and less intense shocks

-shows the link between serotonin and aggression

- males are more aggressive than females

- it has a role in regulating social behaviour via its influence on certain areas of the brain implicated in aggression

-Gimmanco found increasing levels of testosterone in animals via an animal study made them more aggressive.

-Dolan found a positive correlation between testosterone levels and aggresive behaviour in a sample of 60 male offenders , these man had history of psychopathy and impulsive violent behaviour

Mazur= Biosocial model of status (Bmos) to explain the link between testosterone and aggression

testosterone levels change over the course of the day, especially in response to social reactions related to status (competetion) 

Josephs- measured  changes in males testosterone levels before and after a competitive game (which they all lost). They were asked of they would rather compete against their victorious opponent or do an unrelated task.

-the losers who lost and wanted to rechallenged their testosterone levels rose to 73% Of the losers whos testosterone dropped, only 23% re challenged.

-this increases validity 

Carres and MEHETA- came up with a dual hormone hypothesis, inwwhich states high levels of testosterone only increase aggresive behaviour if cortisol levels are low. When cortisol is high, testosterones influence on aggressive behaviour is blocked. Popma did an experiment which supports this, , so the combined influence of cortisol and testosterone may be linked