Biological mechanisms in aggression

• What is the limbic system as a neural mechanism in aggression 


  Processes + responds to environmental stimuli

  Amygdala= regulates emotional response to stimuli, when stressor noticed it sends stress signals to hypothalamus which activated sympathetic branch of ANC > flight or fight response (aggression is fight)
• What is serotonin as a neural mechanism in aggression

  neurotransmitter with inhibitory effect > negatively charged neurons less likely to fire, less serotonin in pre frontal cortex leads to higher levels of neuronal firing which can lead to less self control and therefore higher aggression
• What is testosterone as a hormonal mechanism in aggression 


  androgen made in testes, associated with aggression levels because men with high test found to be aggressive- male prison studies found positive correlation between testosterone and aggression
• What are genetic mechanisms in aggression 


  its hereditary: vunerability increases with genetic similarity, twin studies found concordance rates of 50% for monozygotic; 19% diozygotic
• What are candidate genes as a genetic mechanism of aggression

  MAO-A controls level of monoamine oxidase -A enzymes which regulates serotonin, low level variant (MAO-A L) disrupts serotonin system leading to less self control and more aggression
• Strength of serotonin as a neural mechanism for aggression

  research support, game where proposer offered to split £100 with responder > found when responder rejects offer scans show increase of amygdala activity on FMRI, aggression + amygdala levels reduced when benzodiazepines taken
• Strength of serotonin as a neural mechanism for aggression

  Research support, compare serotonin breakdown product 5-HIAA levels of violent impulsive+ non impulsive offenders > lower in impulsive group which shows aggression linked to serotonin
• Weakness of testosterone as a hormonal explanation for aggression

  Dual hormone hypothesis says test and cortisol involved, cortisol deals with stress > high T low C increased aggression, high C blocked aggressive influence of T
• What is a weakness of genetics as a mechanism for explaining aggression

  Methodological limitations of twin studies > concordance rate not 100% so not all genetics and some environment included
• What is a strength of candidate genes as a genetic mechanism for explaining aggression

  research support, men with high+ low activity MAO-A variant played money distribution game. High variant was more aggressive but low variant were more cooperative when told others were cooperative
• What is a weakness of candidate genes as a genetic mechanism for explaining aggression

  Alternate explanation of MAOA gene and aggression correlation is only in trauma victims > interaction of diathesis stress model
• What is a weakness of candidate genes as a genetic mechanism for explaining aggression

  real world application > use of genetics in justice system. Free will or determinism controversial excusing people