neuronal and hormonal mechanisms

Question 1

what is the limbic system

Answer 1

Papez and Maclean linked limbic system to aggressive behaviours
= area of brain which helps coordinate behaviours that satisfy emotional urges, e.g., aggression/fear

made up of; hypothalamus, amygdala and parts of hippocampus

Question 2

link between amygdala and aggression
(neuronal)

Answer 2

• amygdala play crucial role in assessing threats/triggering emotional responses
• reactivity of amygdala = important predictor of aggressive behaviour
  (more responsive, more aggressive)

Gospic et al found increased activity in amygdala during aggressive responses to provocation (aggression decreased when activity did), using fMRIs

Question 3

what effect did taking benzodiazepine before provocation have in Gospic et al’s study

Answer 3

benzodiazepine = reduce arousal of ANS
- decreased amygdala activity
- reduced number of aggressive responses

Question 4

link between serotonin levels in orbitofrontal cortex and aggression
(neuronal)

Answer 4

normal levels of serotonin (inhibitory NT) in OFC = linked with reduced neurone firing
= associated with greater behavioural self-control

• serotonin deficiency hypothesis = reduced self-control = increase impulsive behaviour, incl aggression

Question 5

link between testosterone and aggression
(hormonal)

Answer 5

many observations = men generally more aggressive than women (T levels around 8x higher than in females)

castration studies show
- removal of testes = reduce aggression in males in many species
- injecting testosterone in same animals = restore aggressive behaviours

Question 6

link between progesterone and aggression

Answer 6

Ziomkiewicz et al = negative correl. between progesterone levels and self-reported aggression

• lowest levels = during and just after menstruation, lower levels = increased aggression

Question 7

strength of neuronal mechanism explanations

Answer 7

research support for serotonin link

berman et al = pps given paroxetine (increase S levels) or placebo
= pps took part in lab-based game, involve giving/receiving electric shocks in response to provocation (e.g., insults)

findings = paroxetine group consistently gave fewer/less intense electric shocks

= evidence of causal link

Question 8

strength of hormonal mechanism explanation

Answer 8

research supporting testosterone link

giammanco = increase in T levels and aggressive behaviours in male rhesus monkeys during mating season
- castration in rats reduce T and mouse-killing behaviours, opposite effect in female rats when injected with T

= support linkage in range of animal species

Question 9

weakness of neuronal mechanism explanations

Answer 9

not only limbic structures linked to aggression
- limbic structures funtion along with OFC (non-limbic)

coccaro et al = reduced OFC activity (less impulse-control) in psychiatric disorders featuring aggression, e.g., bipolar/SZPN

= suggests neural regulation of aggression more complex than theories focusing on limbic structures suggest = limited

Question 10

weakness of hormonal mechanism explanations

Answer 10

limited explanation

• dual-hormone hypothesis
  = high T levels only lead to aggressive behaviour when cortisol levels (role in chronic stress response) are low (antagonistic relationship)

= combined activity of the 2 may be better prediction of aggression than T alone

Question 11

weakness of both explanations

Answer 11

use of animal studies
= may provide useful starting point for understanding/offering valuable insight
- humans differ/much more complex than animals

= findings cannot be directly extrapolated to human experiences/behaviour