Neural mechanisms -aggression

Neural mechanisms -aggression

1. LOW levels of SEROTONIN & HIGH levels of DOPAMINE =INCREASED aggression

2. SEROTONIN AO1

   • ~Our 'happy chemical', which in normal levels has a calming effect on neural firing of the amygdala; the part of the brain responsible for emotion. ->serotonin inhibits responses to emotional stimuli which may otherwise lead to an aggressive response.
     • ~If there are low levels of serotonin in the brain, there is less inhibition of the amygdala thus a stronger likelihood of aggressive behaviour. -> Low levels of serotonin have been linked to impulsive behaviour, aggression & violent suicide.
   • ~Mann et al 1990 ->defenfluramine = depletes serotonin. ->used Q's to find out hostility & aggression score =found incr in males.

3. DOPAMINE AO1

   • ~Is a nerotransmitter that helps control the brain's reward & pleasure centres. High levels have been associated with risk taking behaviour & aggression. ->due to the feeling of pleasure experienced, individuals are likely to continue to engage in aggressive behaviours.
     • ~Amphetamines incr dopamine activity & incr aggressive behaviour.
       • ~Antipsychotics decr dopamine activity & decr aggressive behaviour

4. + Research support ->meta analysis = found lower levels of serotonin in individuals described as being aggressive ->but no significant rise or fall in dopamine levels. ->reduced levels of serotonin were particularly marker in individuals who had attempted suicide =serotonin depletion leads to impulsive behaviour =aggressive behaviour

5. +RWA serotonin-> anti-depressants, proven to clinically raise serotonin levels =lowering in agg. Bond established that such drugs tend to reduce irritability & impulse agg =should be prescribed to reduce self-harm & other forms of agg.

6. + Research support -animals -Raleigh et al =role of serotonin ->gave vervet monkey experimental diets ->high tryptophan =decr agg, whilst fed on diets low in tryptophan = incr agg behaviour. =findings suggest that difference in aggression is related to serotonin levels.

7. + research support -Ferrari et al (2003) -dopamine & serotonin. ->rat allowed to fight for 10 consecutive day at same time ->day 11 =not allowed to fight ->levels of serotonin & dopamine measured. =in anticipation of a fight, the rat's serotonin levels decr =suggests the rats brain chemistry had be changed.

   • -However it's unclear whether the high levels of dopamine are a cause or an effect. =found that individuals will seek out an aggressive encounter solely because they experience a rewarding sensation from it. ->the incr in dopmaine may be a consequence rather than a cause of the agg behaviour =Bi-directional model.

8. -Animal studies =breaching of ETHICAL guidelines -> HARM may be caused -> ALTERING diets =long term health implications -> unable to CONSENT

   • -Animal studies ->attempting to apply findings to human aggression. ->humans have more complex cognitive abilities. ->animals cannot communicate the reasons for their agg =lack validity. ->animal behaviour may be incorrectly interpreted.

9. - neural mechanisms aspect of the biological explanations can be seen as reductionist. to state that aggression is purely down to the level of activity of 2 neurotransmitters is very simplistic. -doesn't take into account environmental triggers. ->the diathesis-stress model may therefore provide a more complex pic.