aggression- neural and hormonal mechanisms in aggression Flashcards
what is the role of the limbic system and who was it linked by?
Papez (1937) and Maclean (1952) linked the limbic system to emotions e.g. aggression
what makes up the limbic system?
hypothalamus, amygdala and parts of the hippocampus
what is the role of the amygdala in aggression?
-the more reactive the amygdala the more likely aggression will be shown
what did brain scans find about lab-based games and aggression?
Gospic et al. (2011)
what did Gospic et al. (2011) find about aggression?
used brain scans (fMRI) w p’s in a lab-based game that provoked aggression
(Gospic et al.) what were aggressive responses associated with?
fast and heightened response by the amygdala
(Gospic et al.) what is the affect of benzodiazepine taken before the game?
-Benzodiazepine reduces arousal of the autonomic nervous system
-decreases amygdala activity and decreased aggression
what serotonin levels are associated with aggression??
low levels
decreased serotonin disturbs this mechanism, reduces self-control and increases impulsive behaviours, including aggression
what do normal levels of serotonin do?
normal levels in the orbitofrontal cortex inhibit neurons (reduced firing) are linked to greater behavioural self-control
what did denson et al. (2012) find about serotonin and aggression?
decreased serotonin disturbs this mechanism, reduces self-control and increases impulsive behaviours including aggression
what did Virkkunen et al. (1994) find about serotonin and aggression?
-lower levels of serotonin metabolite 5-HIAA in violent impulsive offenders compared to non-impulsive offenders
what is the role of testosterone in aggression?
helps regulate social behaviour via influence on brain areas involved in aggression
what did Daly and Wilson (1998) argue about males and aggression?
males more aggressive towards other males at 20+ years when testosterone levels peaks
what did Dolan et al. (2001) find about testosterone and aggression?
found + correlation between testosterone and aggression in males offenders w histories of impulsively violent behaviour
what do animal studies show about aggression and testosterone
-they show testosterone and aggression are linked
-Giammanco et al. 2005
-removing testes (castration) reduces aggression in many species
-injecting testosterone restores aggressive behaviour
what affect does progesterone have on aggression?
-low levels are linked to aggression in women
what does Ziomkiewicz et al. 2012 argue about hormones and aggression in women?
-negative correlation between progesterone levels and self-reported aggression
-progesterone varies in menstrual cycle
ao3- non-limbic brain structures are still involved (limitation)
-limbic structures function jointly w non-limbic orbiofrontal cortex (OFC)
-this is involved in impulse-regulation and inhibition of aggression
-Coccaro et al. (2007) claim OFC activity is reduced in psychiatry disorders featuring aggression, disrupts OFC’s impulse-control so increases aggression
-shows neural regulation is more complex than theories focusing on the amygdala suggest
what did Coccaro et al. (2007) claim about OFC activity?
-claimed OFC activity is reduced in psychiatric disorders featuring aggression- disrupts the OFC’s impulse-control function, increasing aggression
ao3- research into effects of drugs on serotonin (strength)
-Berman et al.’s- lab bed game. giving and receiving electric shocks in reposter to provocation
-p’s who took paroxetine (enhances serotonin) gave fewer and less intense shocks than placebo group
-evidence of a causal link between serotonin and aggression
ao3- direct or indirect?? (limitation)
-neural factors may be directly linked to aggression e.g. Gospic, serotonin also reduces aggression by inhibiting neuronal activity
-but neural factors may be indirect (Denson et al.) found a link between serotonin and aggression but other factors may influence this link
-evidence neural mechanisms related to aggression is strong but relationship is probably not direct
ao3- research with non-human animals (strength)
-Giammanco et al. (2005) review confirms the role of testosterone, e.g. increase of testosterone and aggression in male rhesus macaque monkeys during mating season
-in rats, castration of males reduces testosterone and mouse-killing. injecting femalerats with testosterone increases both
-findings show that testosterone pallets a key role in aggression in a range of animal species
ao3- evidence linked testosterone and aggression is mixed (limitation)
-Carré and Mehta’s (2011) dual-hormone hypothesis suggests high levels of T leads to A but only when cortisol levels are low
-high cortisol blocks T’s influence on A. cortisol is a hormone that’s key to the body’s chronic stress response
-so combined activity of T and cortisol may be better predictor of aggression than either hormone alone
