Neural and Hormonal influences

Neural and Hormonal influences

1. Neural

   • Limbic system
     • coordinates behaviours that satisy emotional and motivational urges
     • amygdala = evaluates emotional importance of sensory info
       • if stimulated, aggressive reposnse
       • if removed means no longer able to respond to stimuli
     • Hippocampus = formation of LTM, compare current with past experiences
       • impaired hippocampus means respond inappropriately to sensory info (Bocardi)
   • Seretonin
     • inhibits the firing of the amygdala
     • low levels of sereotnin remove inhibitory effect
     • less able to control aggressive behaviour

2. Hormonal

   • Testosterone
     • removing testosterone results in lower levels of aggression
     • Daly and Wilson
       • 21-35 = testosterone levels are highest, increase in male on male activity
     • increase amygdala activity
       • during time of social threat

3. Neural evaluations

   • evidence for amygdala
     • Pardini
     • males with lower amygdala volumes are more aggressive
     • amygdala volume compromises ability
     • predict development of persistent aggression
   • evidence for hippocampus
     • Raine
     • escaped conviction and those who didn't (acted more impulsively)
     • MRI scans showed asymmetries in hippocampus when more impulsive
     • shows impaired hippocampus works with amygdala
   • evidence from non human species
     • Raleigh
     • vervet monkeys who fed on high tryptophan diet (increase serotonin)
     • less aggressive when on high tryptophan
     • shows aggression caused by serotonin levels

4. Hormonal evaluations

   • inconsistent evidence
     • many studies show +ve relation between testosterone and aggression
     • some show no correlation
     • Albert = correlation between testosterone and self reported aggression but no correlation between testosterone and actual aggression
     • unclear relationship
   • dominance or aggression
     • in animals the influence of testosterone on aggression is shown through dominance
     • more varied in humans
     • Eisternger = testosterone could make women act nicer, depending on the situation therefore testosterone promotes social seeking behaviour