neural, hormonal and genetic influences on aggression

Question 1

role of the limbic system

Answer 1

Papez and Maclean linked the limbic system to emotional responses involving aggression
the limbic system is composed of the hippocampus amygdala and the hypothalamus
the reactivity of the amygdala is a good predictor of the aggression in mammals the more reactive the more aggressive

Question 2

evidence for role of amygdala

Answer 2

Gospic- some participants subjected to mild provocation when reacting aggressively fMRI scans showed heightened and fast activity in the amygdala
a benzodiazepine was given to people which reduces activity of the autonomic nervous system leading to the decreased activity in the amygdala and reduced aggression

Question 3

Orbifrontal cortex and seretonin

Answer 3

Seretonin has widespread inhibitory effects in the brain (slow down and calms neural activity)
normal levels of Seretonin are associated with behavioural self control. decreased Seretonin disrupts aggression.

Question 4

twin studies

Answer 4

suggested that heritability accounts for about 50% of variance in aggressive behaviour
Coccaro twin study on male MZ and DZ twins.
concordance rates were 50% in MZ twins and 19% in DZ which illustrates that genetic factors have a stronger impact on aggression than environmental because mz is higher than dz concordance rate. however shouldnt be used singularly to explain aggression as conc rates are not 100 and 50.
Rates were also lower for verbal aggression- 28 and 7%

Question 5

adoption studies

Answer 5

Mednick adoption study - 1400 adoptees from denmark convicts
most had a biological parent who was a convict
- correlation does not mean causation

Question 6

MAOA gene

Answer 6

controls production of the enzyme monoamine oxidase A (MAO-A)
this enzyme regulates neurotransmitters serotonin, dopamine and noradreneline

Question 7

MAOA-L

Answer 7

variation of MAOA gene linked to high levels of aggression
-less production of the enzyme that metabolises serotonin
-less serotonin metabolised therefore low levels of serotonin because it isnt constantly being metabolised.

Question 8

MAOA-H

Answer 8

-higher production of enzyme that metabolises serotonin
-meaning high levels of serotonin constantly metabolised
-meaning high levels of aggressive behaviour

Question 9

family study

Answer 9

BRUNNER -large dutch family who displayed large amounts of aggression
5 males carried fault MAOA gene
no females were affected by the genetic dysfunction.

Question 10

gender differences (chromosomes)

Answer 10

MAOA gene is carried on the X chromosome so even if a female carries the dysfunctional faulty MAOA gene it is likely the corresponding gene will have the MAOA gene which will be expressed over the faulty one because it is found to be dominant.

Question 11

animal research