neural explanations Flashcards
what is the biological explanation for aggression?
aggression is due to the structure and/or function of our body, our genes, brain anatomy, hormonal or neuronal activity
what is the limbic system?
A network of structures deep in the brain
Papez and Maclean (1952) identified the limbic system as comprising of the hypothalamus, amygdala, parts of hippocampus and thalamus etc. For aggression, amygdala is most important
what is the amygdala’s role?
It’s key role in human and non-human animals is how they assess and respond to environmental threats and challenges. The reactivity of the amygdala in humans has been seen to be an important predictor of aggressive behaviour
what did Gospic find in 2011?
Gospic used a well know lab method of assessing aggressive behaviour known as the ultimatum game which features two players and money being offered to being split in certain ways.
PPs played as responders whilst having an fMRI (objective measure)
researchers found that when responders rejected unfair offers (aggressive reaction to social provocation), scans revealed a fast and heightened response by the amygdala.
what was found by Gospic when participants took BZs before the game?
BZs are drugs to decrease amygdala activity, and when these were taken before the game, there were two effects found on responses to unfair offers. It halved the number of rejections (ie reduced aggression) and decreased activity in the amygdala.
Strong evidence of an association of reactive aggression and amygdala activity.
what was found when the amygdala was stimulated in cats
a fearful or anger responses was created
what did Bushman find with rats?
rat lesion studies suggest different types of aggression may be controlled by different subsets of brain structures
-limbic subcortical sites involved are amygdala, hypothalamus amongst others
what did Raine find with PET scans?
Raine 1997 used PET scans to look at 41 murderers brains and 41 controls. They found abnormalities in the functioning of the limbic system implicated in aggression.
Raine 2000 also found that the prefrontal cortex which inhibits aggressive behaviour was 14% less active than normal in non-abused murderers & 15% smaller in anti-social males
correlational - suggests brain anomaly could be a factor involved in explanations of aggression but doesn’t necessarily cause it, could be the other way round
what is the case study of Charles Whitman?
Texan marine who murdered his family and shot a dozen strangers in a killing spree before taking his own life. He left a note begging for his brain to be studied and his autopsy revealed he had a tumour pressing on his amygdala
Sumer case study
case study of 14 year old girl who was epileptic and violent - diagnosed with tumour in limbic system following MRI and after drug therapy became less aggressive with more normal levels of behaviour suggesting high levels of aggression could have been prompted by the tumour in the limbic system.
Phineas gage
rod damaged pre-frontal cortex
this region is implicated in personality changed and aggression/violence
within months his personality changed dramatically
- he became extravagant and anti-social, a foul mouth liar with bad manners and frequently got into fights and assaults
- could no longer hold a job or a plan
how does alcohol affect aggression?
individuals prone to aggression are more likely to drink & become aggressive while drunk - alcohol affects brain
alcohol reduces self-awareness & disinhibits (deindividuates), it also switches off the pre-frontal areas, leaving the aggressive limbic areas without cognitive control
what is the evaluation of the limbic system as an explanation of aggression?
the role of the limbic system is not clear cut, the system is made up of many components and the extent to which each different structure is involved isn’t fully understood, equally it could be an interaction of the various components
research supporting the link between aggression and brain abnormalities is only correlational. In addition, not all people with limbic system abnormalities display aggressive behaviour. We cannot therefore ascertain c+e
what neurotransmitters are linked to aggression
high levels of dopamine and low levels of serotonin
what is serotonin
a neurotransmitter that has a widespread inhibitory effect on the brain
it slows down and dampens neuronal activity
normal levels of serotonin are linked with reduced firing of neurons, and this is associated with a greater degree of self-control
decreased serotonin may well disturb this mechanism, reducing self-control and leading to an increase in impulsive behaviour e.g. aggression (Denson 2012)
