Flashcards in Structures of the brain - Aggression Deck (14):
How can brain damage cause aggression?
- Abnormalities in the prefrontal cortex = less control of impulses as the lymbic system could be able to make decisions with out the PC being able to inhibit it
- Abnormalities/increased size of amygdala = increase of angry emotions
How does serotonin increase aggression?
Low levels = less able to inhibit aggressive impulses
Why is serotonin hard to measure?
Can be tested through cerebral spinal fluid or through levels of receptors in the brain. Can only look for receptors after death. (ISSUE = hard to tell if aggressive people lack it)
- If there are more receptors than usual, the brain has chronic low levels of serotonin
How does dopamine increase aggression?
- High levels of dopamine are associated with high levels of aggression. Provides reward after aggressive behaviours
- Amphetamine abuse increase dopamine and is also associated with aggressive behaviour
What did Rainea do?
Studied murderers pleading not guilty by reason of insanity claiming brain dysfunction.
What did Rainea find?
- Murderers were characterised by reduced glucose metabolism (brain isn't working as much) in the prefrontal cortex.
- Abnormal activity in the amygdala = suggesting they would be more aggressive
What did Mann et al find?
Drug dexfenfluramine depletes serotonin levels in the brain = aggression increased among males but not females
What did Couppis et al find?
Dopamine causes individuals to seek out aggression because of the rewarding sensations
What is the real world applications issue?
Should violent offenders be punished if they have damage to the prefrontal cortex = is it their fault they're aggressive?
What is the nature/nurture issue?
Nature explanation could be that individuals are born with a brain malfunction in the prefrontal cortex or amygdala
What did Ferrari et al do?
Tested the influence of serotonin and dopamine on rats aggression:
- allowed the rat to fight everyday for 10 days
- on 11th day the rat was not allowed to fight
What did Ferrari et al find?
On the 11th day in anticipation of a fight dopamine levels were high and serotonin levels were low
What does Ferrari et al's study show?
Experience had changed brain chemistry = created aggression