Neural - Serotonin

Neural - Serotonin

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   • Serotonin in normal levels can exert a calming, inhibitory effect on neural firing in the brain. Thus, causing a reduction in aggressive behaviour by inhibiting responses to emotional stimuli that might otherwise lead to an aggressive reaction.
     • Claimed that low levels of serotonin, particularly in the prefrontal cortex, removes the inhibitory effect and individuals are less able to control their impulsive behaviours - such as aggression or violent suicide.
   • Many studies have shown a negative correlation between serotonin levels and aggression.
     • Evidence for the role of serotonin comes from studies where serotonin levels have been manipulated. Mann gave 35 pts dexfenfluramine - a drug known to reduce serotonin levels. Then a questionnaire was used to assess hostility and aggression score and found levels increased after taking the drug - although only in males

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   • Raleigh et al studied vervet monkey's and found that those who fed on a diet high in tryptophan (increases serotonin levels in the brain) showed decreased levels of aggression. Those who had diets that were low in tryptophan exhibited increased aggressive behaviour. This suggests that the difference in aggression could be attributed to serotonin levels and that components of your diet can contribute to the level os your aggressive behaviour.
     • This research was done on animals and cannot be generalised to humans because of the complex brain structure that humans possess. This suggests that the aggression levels seen by the monkey's can't be said to be the same as humans as there may be a more varied effect regarding what tryptophan does on the brain, and therefore, aggression levels.
   • A meta-analysis of 29 studies (Scerbo & Raine) examined neurotransmitter levels in anti-social children and adults. Found lower levels of serotonin in individuals described as being aggressive. Reduced serotonin levels were particularly marked in those individuals who had attempted suicide. This suggests that serotonin reduction leads to impulsive behaviour, which may lead to aggressive behaviour in various forms.
     • Research into neural mechanisms in aggression is correlational meaning that it's difficult to determine whether the biological mechanisms cause aggression or whether changes in neurotransmitters are the effect of aggression. This makes it difficult to determine whether or not low levels of serotonin do cause aggression and if we should be eg. seeking foods that trigger high levels of serotonin in order to reduce aggression.