neuronal and hormonal mechanisms

Question 1

what are the two sections of the biological approach?

Answer 1

•neural
•hormonal

Question 2

what does the neural explanation cover?

Answer 2

the nervous system, brain structures, neurotransmitters

Question 3

what does the hormonal explanation cover?

Answer 3

•chemical messengers that are released by glands into the bloodstream, hormones, testosterone, cortisol

Question 4

what is the limbic system?

Answer 4

•primitive area of the brain
•highly involved in emotion
•found in animals and humans
•activates immediate response to threats

Question 5

what are the 4 sections of the brain in the limbic system? which are the two main ones in aggression?

Answer 5

•amygdala
•hippocampus
-hypothalamus
-thalamus

Question 6

what does the amygdala do?

Answer 6

•it detects threats and initiates a response
•the more reactive it is, the more aggressive the person is

Question 7

what does the hippocampus do?

Answer 7

•it plays a significant role in learning and memory formation- linking memory with emotion
•impairment of the hippocampus means that stimuli may be wrongly interpreted, for example interpreting non-aggressive stimuli as aggressive

Question 8

how do you describe the location of the limbic system?

Answer 8

subcortical

Question 9

what is the function of the thalamus and the hypothalamus?

Answer 9

•hypothalamus triggers fight or flight response
•thalamus acts as a sensory hub, sends information to different areas of the brain

Question 10

is serotonin a neural or hormonal mechanism?

Answer 10

neural

Question 11

what role does serotonin have in aggression?

Answer 11

•serotonin is an inhibitory neurotransmitter with calming effects on the brain
•normal levels slow down and dampens neuronal activity in the amygdala
•decreased serotonin disturbs this mechanism leading to increased activity in the amygdala and increased aggression (serotonin deficiency hypothesis)
•research has shown that drugs which decrease serotonin lead to increased hostility and aggression

Question 12

what role does the hormonal mechanism testosterone have in aggression?

Answer 12

•animal studies show that experimental increases in testosterone are related to greater aggressive behaviour in several species, castration decreases aggression
•researchers have found a positive correlation between testosterone levels and aggression in 60 male offenders in UK maximum security hospitals
•testosterone also influences the activity of serotonin in the brain, it can reduce its activity

Question 13

what to talk about when asked about neural explanations:

Answer 13

•the limbic system- amygdala and hippocampus. abnormalities in these structures are linked to increased aggression
•low levels of serotonin are implicated in aggression

Question 14

what to talk about when asked about the hormonal explanation:

Answer 14

•high levels of testosterone associated with aggression

Question 15

what is the correlation between serotonin and aggression?

Answer 15

negative correlation

Question 16

strength: supporting research

Answer 16

•supporting research for the involvement of the limbic system in aggression has been provided by Raine
•they studied violent criminals and found that the MRI brain scans of those who acted impulsively had hippocampal asymmetry.
•this may impair the ability of the limbic system to work effectively when processing emotional information
•in turn, leading to inappropriate and aggressive verbal and physical responses
•this clearly demonstrates that abnormalities in the limbic system are linked to aggressive behaviour

Question 17

other involvement

Answer 17

•evidence from human brain studies implicated the orbitofrontal cortex, not just the limbic system in aggressive behaviour
•the OFC plays a key role in self control in humans
•findings from Coccaro provide evidence of OFC dysfunction in individuals with a history of impulsive aggressive behaviour when presented with social threat signals (angry faces)
•this suggests that there are more parts of the brain involved in contributing to aggressive behaviour and this can be useful in creating treatments for overly aggressive individuals

Question 18

something else

Answer 18

•Raine studied violent criminals and found that the MRI brain scans of those who had acted impulsively showed hippocampal asymmetry across the two hemispheres (a smaller hippocampus in the left hemisphere)
•this may impair the ability of the limbic system to work effectively and process emotional information correctly
•in turn, leading to inappropriate and aggressive verbal and physical responses

Question 19

another one

Answer 19

•serotonin reduces impulsive unprovoked aggression
•in a three month, double-blind, placebo-controlled study they evaluated the anti-aggressive efficacy of fluoxetine in 40 patients with personality disorders and a prominent history of impulsive aggression
•compared with a placebo, fluoxetine led to a significant reduction in scores for verbal aggression, aggression against objects and irritability
•the results provide evidence that serotonin reuptake inhibitors (SSRIs) can diminish impulsive aggression independent of their antidepressant action in certain individuals

Question 20

last one

Answer 20

•a complication in terms of understanding the role of testosterone in aggression concerns the dual hormone hypothesis
•this proposes that in humans, testosterone’s influence on behaviour depends on cortisol, such that testosterone only increases aggressive behaviours when cortisol is low
•supporting this, many of the recent studies showing an influence of testosterone on risk behaviour and status position find this only applies for low-cortisol individuals