Neural and Hormonal

• What is the limbic system


  A central area of the brain thatregulates emotional urges.
• Limbic system and aggression


  The amygdala is a structure within the limbic system that prevents injury or putting yourself in danger. Thought to have evolved as a fear response, in most people works proficiently to detect fear accurately.Excessively fearful or aggressive people may have issues with the amygdala; could be damaged due to stroke or tumour, may be developmental issues.Depending on where the damage is, could cause an overly fearful reaction or no reaction at all. In overly aggressive responses, the amygala may misinterpret information from senses or cortex and respond with overly aggressive behaviour.Research has shown that when certain areas are stimulated, animals and humans respond in a hostile and aggressive way.Therefore, damage to this area can result in an inappropriate aggressive response to a perceived threat.
• Strength of limbic system as explaination

  Animal studiesshow that if certain areas of the amygdala are stimulated electrically, then the animal will respond aggressively by snarling.If these areas of the amygdala in animals are removed, then the animal will no longer respond in the same way. This provides evidence that the amygdala located in the limbic system may be responsible for aggressive behaviour.

  Sumer et al (2007)reported a case study of a 14-year-old girl who was showing aggressive, anger and rage. An MRI scan discovered a tumour in the limbic system and after the tumour was treated with drugs, the patient's levels of aggression returned within "normal" levels.This suggests that tumours in the limbic system could be the cause of aggressive behaviour.
• Frustration-aggression theory - Limitation


  Analternative explanationthat provide a better understanding of human is aggression is provided byFrustration aggression theory. According to Dollard, frustration leads to aggression. This hypothesis is based on the psychodynamic concept of catharsis and views aggression as a psychological drive similar to a biological one such as hunger. If our attempt to achieve a certain goal is blocked such as trying to get past in a busy pub, we experience frustration. This in turn leads to swearing or an aggressive drive such as a violent fantasy or violence.
• Deindividuation theory - Limitation (alternative theory)


  When we are part of a crowd, it is possible for us to lose our sense of identity and responsibilityand in these circumstances, the social norms that usually keep us restrained with regards to antisocial behaviour are temporarily forgotten. We live for the moment, we stop monitoring and regulating our own behaviour and the result is antisocial/aggressive behaviour, for example crowd violence at football matches.This is a psychological explanation for aggression and therefore challenges the view that the limbic system is solely responsible for aggression.
• The role of serotonin

  Serotonin, which is a neurotransmitter, is thought to reduce aggression by inhibiting responses to emotional stimuli that might otherwise lead to an aggressive response.Normal levels of serotoninin the orbitofrontal cortex are linked with a reduced firing of neurons, and isassociated with greater self-control(less-likely to engage in aggressive behaviour).Low levels of serotonin have been linked with an increased susceptibility to impulsive behaviour, aggression and even violent suicide
• Strengths of serotonin


  Raleigh et al (1991)found that monkeys fed on a diet high intryptophan(which increases serotonin levels in the brain) exhibited decreased levels of aggression and vice versa.This also demonstrates that low levels of serotonin are linked to higher levels of aggressionsuggesting that aggressive behaviour "may" be biologically determined.

  Virkkunen et al (1994)compared levels of a serotonin breakdown product in violent impulsive and violent non-impulsive offenders.The levels were significantly lower in the impulsive offenders, and they also suffered from more sleep irregularities (serotonin regulates sleep patterns). This supports the notion that impulsive aggression can be linked to neurotransmitters.
• Limitations of serotonin


  Biochemistry is adeterministic explanationfor aggression, removing the notion of free will and choice over our aggressive responses and instead laying the blame with neurochemistry in the brain.

  Alternative explanation- e.g. SLT
• The role of testosterone

  Testosterone is a male hormone produced mainly in the testes and is associated with sexual and aggressive behaviour.Males are generally more aggressive than femalesand at the age where testosterone levels are at their highest (21-35) there is an increase in male to male aggression. Attention has therefore focused on the male sex hormone testosterone, an androgen responsible for the development of masculine features.It may be that changes in testosterone influence aggressionby increasing amygdala activity.
• Wagner - AO3 strength

  Observed reduced levels of aggression in mice after they were castrated (reducing testosterone). Furthermore,the mice returned to normal levels of aggression after they were supplemented with testosterone injections. This supports the research that testosterone and aggression are linked. However, animal study...
• Limitations of testosterone as an explanation

  Animal studies

  aternative explanatione.g. frustration aggression theory