neuronal and hormonal mechanisms Flashcards
what is the limbic system
Papez and Maclean linked limbic system to emotional behaviours
made up of; hypothalamus, amygdala and parts of hippocampus
link between amygdala and aggression
- reactivity of amygdala = important predictor of aggressive behaviour
(more responsive, more aggressive) - influence how mammals respond to/assess environmental threats
evidence supporting role of amygdala
Gospic et al (2011)
- pps subjected to mild provocation
- reacted aggressively = fMRI scan shows fast and heightened response by amygdala
what effect did taking benzodiazepine before provocation have in Gospic et al’s study
benzodiapine = reduce arousal of ANS)
- decreased amygdala activity
- reduced number of aggressive responses
link between serotonin levels in orbitofrontal cortex and aggression
normal levels of serotonin in OFC = linked with reduced neurone firing
= associated with greater behavioural self-control
- serotonin deficiency = reduced self-control = increase impulsive behaviour, incl aggression
link between testosterone and aggression
many observations = men generally more aggressive than women
castration studies show
- removal of testes = reduce aggression in males in many species
- injecting testosterone in same animals = restore aggressive behaviours
link between progesterone and aggression
Ziomkiewicz et al = negative correl. between progesterone levels and self-reported aggression
- lowest levels = during and just after menstruation
strength of neuronal mechanism explanations
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
strength of hormonal mechanism explanation
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
weakness of neuronal mechanism explanations
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
= suggests neural regulation of aggression more complex than theories focusing on limbic structures suggest = limited
weakness of hormonal mechanism explanations
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
