It may be that low levels of cortisol are the product of low autonomic nervous system ANS arousal, and that people with low cortisol levels seek behaviours that arouses their ANS.
As there is also evidence that the frontal lobes are involved in the control of aggressive impulses it may be low serotonin in this area of the brain that increases the aggressiveness of some individuals. However, this assumes that suicide is inwardly directed aggression. Similarly, Mann et al found among suicide completers, those with increased numbers of serotonin receptors chose more violent methods of suicide.
This study would suggest that more guns would lead to more violent behaviour. AO3 It is possible aggression is not caused by low levels of serotonin but by low serotonin metabolism which leads to increased numbers of receptors.
This may be due to the fact that cortisol increases anxiety and the likelihood of social withdrawal. However, a meta-analysis conducted by Scerbo and Raine challenges the link between dopamine and aggression.
In mice, a reward pathway in the brain is engaged in response to an aggressive event, with dopamine being a positive reinforce. Archer et al Women with night testosterone had higher occupational status as a result of being more assertive.
There is some evidence for this point of view. Arora and Meltzer found a relationship between violent suicide and elevated serotonin receptor density in the pre-frontal cortex. The link between neurotransmitters and aggression largely ignores the important role played by social factors in aggression.
They suggest that people may seek out aggressive encounters because dopamine is released as a positive reinforcer whenever they engage in aggressive behaviour.
Another theory that also criticises neural and hormonal mechanisms is deindividuation. In this statement, scientists from 12 different countries formally challenged a number of popular beliefs based on scientific findings with animals and humans that had been used to justify violent behaviour in humans.
Therefore low levels of serotonin may lead to increased susceptibility to impulsive behaviour and aggression. They found that aggressive participants had lower levels of 5-HIAA than the non-aggressive participants, which again supports an association between low serotonin activity and aggression.
It is very difficult to effectively research the role of dopamine in aggression and establish a causal link, due to the fact that dopamine is an essential neurotransmitter for many behaviours including the control of movement.
Book et al conducted a large meta-analysis of 45 studies and found a weak positive correlation between testosterone levels and aggression. Brown et al supports this claim. This may lead to injustice such as in the example of a series of cases in the s where hormonal fluctuations around pre-menstrual tension was used as grounds for temporary insanity.
Therefore, a causal relationship cannot be established as it is difficult to explain whether low levels of serotonin and high levels of dopamine influence aggressive behaviour, or if they are a by-product of aggression. The results also cannot be repeated and so are not entirely reliable.
Serotonin and aggression — AO1 Cases showed normal levels of serotonin exert an inhibitory effect on the neuronal firing in the brain. Therefore, the neural explanation of aggression can be criticised for being reductionist as it fails to consider alternative explanations.
Gage suffered an injury in an accident when a tamping iron, 3cm in diameter, passed through his jaw behind his eye and out of the top of his head. Dexenfluramine is a drug that depletes levels of serotonin in the brain.
AO2 It is also reductionist as it takes a simplistic views in explaining of the complexity human behaviour. There was a study where cats had the amygdala removed.
Aggression may be just one form of dominant behaviour. Neural mechanisms Serotonin Two neurotransmitters within the brain are implicated in aggressive behaviour, these are serotonin also called 5-hydroxytryptophan or 5HT and dopamine.
They examined serotonin and dopamine levels in antisocial adults and children, and found that low serotonin levels consistently, but no significant rise or fall in dopamine levels, this suggests that dopamine has no effect on aggression, instead only serotonin has an influencing effect.
Olweus et alstudies the testosterone levels of juvenile offenders and found no significant difference between them and non-offenders, however they did find a slight increase in the testosterone levels of violent juvenile offender in comparison to non-violent ones, and that juvenile with higher testosterone levels were more likely to respond aggressively to challenges from peers and authority figures.
A theory that disagrees with the idea that hormone and neuron mechanisms are the cause of aggression is social learning theory. Arora and Meltzer found a relationship between violent suicide and elevated serotonin receptor density in the pre-frontal cortex.
Zitzmann argues that not only is the link between testosterone and aggression not proven, but that testosterone may also have many positive effects for males.
Neural and hormonal mechanisms in aggression, including the roles of the limbic system, serotonin and testosterone.
Genetic factors in aggression, including the MAOA gene. Neural Mechanisms Serotonin Much of the research on the role of neurotransmitters on aggression has focussed on serotonin activity.
Neural and hormonal mechanisms in aggression.
Neurotransmitters. NTs are chemicals enabling impulses within brain to be transmitted from one area to another. Neural and hormonal mechanisms in aggression. Neurotransmitters. NTs are chemicals enabling impulses within brain to be transmitted from one area to another.
Transcript of Neural, Hormonal, and Genetic Factors in Aggression. Neural, Hormonal, and Genetic Factors in Aggression NEUROTRANSMITTERS Serotonin HORMONAL MECHANISMS GENETIC FACTORS Cortisol Biological mechanisms and aggression is well established in non-human animals, but unclear in humans.
Discuss neural and hormonal mechanisms in aggression. (8 marks + 16 marks) You should outline and evaluate the link between aggression and neurotransmitters such as serotonin and dopamine, and hormones such as testosterone and cortisol. Neural mechanisms and hormones as a cause of aggression Do levels of neurotransmitters, such as serotonin and dopamine, cause aggression?
What is the .Neural and hormonal mechanisms in aggression