Neural and hormonal mechanisms in aggression

The limbic system:

The hypothalamus, the amygdala and parts of the hippocampus

Gospic (2011) money offer game, rejection = aggressive. When participants rejected (aggression) fMRI noticed increased activity in the amygdala. When benzodiazepine (reduces arousal of ANS) taken prior, decreased activity in the amygdala and halved no. of rejections.

Orbitofrontal cortex:

Normal levels of serotonin (in OFC) linked with reduced firing of neurons = greater self-control

The limbic system functions with the OFC

Support for serotonin

Virkkunen (1994) compared violent impulsive and violent non-impulsive offenders and found that significantly lower serotonin levels were in that of impulse offenders

MAOA seratonin-aggression link

The MAOA-L gene causes low activity in the MAO-A enzyme which causes high serotonin meaning more is left for synaptic transmission. HOWEVER, Virkkunen (1994) found that significantly lower serotonin levels were in that of impulse offenders.

Testosterone:

Dolan (2001) found a positive correlation between T and aggressive levels in maximum security prisons.

Progesterone:

Ziomkiewicz (2012) found negative correlation between progesterone levels and self-reported aggression. This suggests low levels are linked to increased aggression.

Support from animal studies

Giammanco (2005) found higher T is associated with higher aggressive behaviour in animal studies (removing testes reduces aggression)

Ignores environmental factors

Berkowitz (1989) frustration primes you for aggression. Weapon effect, pps shocked the other greater when two guns were left on the table compared to sport equipment (6.1 compared to 4.7)