Neural Mechanisms

Neural Mechanisms

1. THE LIMBIC SYSTEM

   • Formed - several structures - amygdala + hippocampus - motivation, emotion, learning + memory AND instinctive beh/s (agg/ + sexual)
   • Most attention for agg/ = amygdala. Sustained Electrical Stimulation = fear+rage responses in lab/ animals + similar findings in humans
   • Zagrodzka et al (1998) - damage - central nucleus of amygdala in cats = agg/ "preditor-like-attacks". Similar results rats + hamsters
     • Justified generalising: underlying neural circuitry related to agg/ = similar across species. Inf/ amyg/ found across range of species
   • Surgical removal of amyg/ reduces agg/ in previously violent indiv/s
     • Side effect: loss of emotion, initiative, enthusiasm (Groves + Schlesinger, 1982). Amyg/ not directly cause agg/ - involved in processing ass/ emotions (anger)

2. THE FRONTAL CORTEX

   • Social regulation + interaction. Agg/ = social interaction.
   • FC - connected to functioning of amyg/ + hypothalamus = inf/ other brain areas stimulate agg/ responses
   • Damage: impulsive beh/, irritability, short temper, easily provoked
   • Raine et al (1997) - PET scans - 41 murders/ non-murderers. Lower levels activity in pre-FC + amyg/. Sig/ difference = kill.
     • Good sized sample, controlled variables (sex, mental illness, drug taking)
     • PET - lack precision, no control over levels of violence (e.g...)Studies took place after murders - only correlational, no cause and effect

3. SEROTONIN

   • Neural mechanisms: neurons, neural circuits, regions of brain + substances (neurotransmitters)
   • Serontonin - enable impulses in brain - transmitted one area to another.
   • Low levels: ass/ agg/. Reduce agg/ beh/ - inhibiting responses to emotional stimuli. Other studies not found link
   • Mann et al (1990) - 35 healthy subjects - drug (dexfenfluramine) - deplete serotonin. Questionnaire - treatment = inc/ hostility + agg/ scores. Males not females
   • Raleigh et al (1991) - Vervet monkeys - diet high tryptophan (inc/ serotonin) - decreased agg/. Low tryptophan = inc/ agg/. Differences attributed to serotonin levels

4. IDA - NATURE/NURTURE: Neural mech/s = nature. Levels of neurotransmitters inf/ by environmental factors (e.g. Raleigh). Interaction

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