Aggression: Neural and Hormonal mechanisms in aggression Flashcards
What are the 2 neural mechanisms thought to be involved in aggression?
the limbic system
serotonin
What is the limbic system?
a group of structures in the brain , including the amygdala , hippocampus and hypothalamus
Make 1 elaborated point about how the limbic system is involved in aggression
it plays a key role in how organisms respond to environmental threats and challenges and is believed to be key factor in whether we respond aggressively or not to external stimuli
Which structure within the limbic system is most related to aggression and why?
the amygdala , as its responsible for attaching emotional significance to sensory information
Who provides supporting evidence for the role of the limbic system in aggression?
Give a however point for this
Zagrodzka et al 1998-damage to the central nucleus of the amygdala in cats led to aggressive behaviour
-similar results have been found with rats and hamsters which suggests the limbic system is a key factor in understanding aggression
However … animal research challenges ability to generalise findings to humans
Who else provides supporting evidence for the role of the limbic system?
Gospic et al 2011- used the ‘Ultimate Game’ method , fMRIs showed heightened activity in the amygdala when responders rejected unfair offer(aggressive reaction) which shows the amygdala is related to aggression
Who provides contradictory evidence for the role of the limbic system?
Raine et al 1997- found lower activity in frontal cortex in murderers compared non murderers which suggests other brain structures have a role in influencing aggression
Give another contradictory point for the role of the limbic system
-research suggests the amygdala doesn’t work in isolation , evidence from the case study of Phineas Gage suggests a role of the frontal cortex
Make 3 points about the role of serotonin in aggression
-low levels of serotonin have been associated with increased aggression in animals and humans
-serotonin is thought to decrease aggressive behaviour by inhibiting responses to emotional stimuli that would normally lead to aggressive behaviour
-less serotonin means communication between the amygdala and frontal cortex becomes weaker so its less likely aggressive responses will be inhibited
Who provides supporting evidence for the role of serotonin?
Mann et al 1990- gave 35 healthy subjects a drug known to lower serotonin and found treatment was associated with an increase in hostility and aggression scores on a questionaire
this supports the role of serotonin , however the sample only included males
What is testosterone?
a sex hormone produced by Leydig cells in the testes and ovaries as well as neuroendocrine cells in the brain
What influence does testosterone have pre-natally?
What influence does testosterone have at time of birth?
influences development of the limbic system
it sensitises neural circuits associated with aggression
What have brain scans of adult males shown about testosterone?
it activates the amygdala which enhances its emotional activity
it also acts on synapses in the serotonin system which lowers amount of serotonin
Who provides supporting evidence for the role of testosterone?
Wagner et al 1979- castrated mice to decrease testosterone levels and found this led to a decrease in aggression
-if then given testosterone , levels of aggression were restored (Subtraction Replacement Paradigm)
Who provides contradictory evidence for the role of testosterone?
McBurnett et al 2000- found boys with low cortisol began antisocial acts at a much younger age and showed 3x the no of aggressive symptoms
suggests a role for both testosterone and cortisol in aggression
