neural and hormonal mechanisms in aggression

Question 1

what does the limbic system mean?

Answer 1

buried deep within the brain a network of structures called the limbic system.

Question 2

what did James papez and Paul Maclean identify for the limbic system

Answer 2

they identified the LS as compromising the cingulate gyrus, septal area, hypothalamus, fornix, amygdala + parts of the hippocampus + thalamus.
Most important - amygdala.

Question 3

what does the amygdala predict

Answer 3

an important predictor for aggressive behaviour

Question 4

what was Katarina Gospic et al laboratory method called?

Answer 4

Ultimatum game - assessed aggressive behaviour.

Question 5

Procedure of Ultimatum game (Katarina Gospic)

Answer 5

-Features two players
-the proposer offers to split money in a certain way with the responder.
- if the responder accepts, the money is split .
-but if rejects both receive nothing.
-partcipants played as repsonders had their brain scanned by fmri, which highlights activity in different areas on the brain.

Question 6

findings of ultimatum game (Katrina Gospic)

Answer 6

when respondents rejected unfair offers scans revealed a fast + heightened response by the amygdala.
also found that benzodiazepine drug (reduces arosal of automatic nervous system) taken before the game had two effects on respondents offers:
-halved number of rejections
-decreased the activity of amygdala.
this strong evidence of an association between reactive aggression + amygdala activity.

Question 7

what is serotonin?

Answer 7

Is a neurotransmitter involved in communication of impulses between neurons. it has widespread inhibitory effects on the brain; slows down + dampens neural activity.

Question 8

what are normal levels of serotonin linked with?

Answer 8

N levels of S in orbital context linked with reduced firing of neurons + this is associated with greater degree of behavioural self-control.

Question 9

what do decreased levels of serotonin do

Answer 9

D S may disturb this mechanism, reducing self control + leading to an increase of impulsive behaviour including aggression. (denson et al)

Question 10

what did Matti virkkunen et al do in relation to serotonin.

Answer 10

compared levels of serotonin breakdown product (5-HIAA) in the cerebrospinal fluid of violent impulsive + violent non-impulsive offenders.
The levels were significantly lower in the impulsive offenders + they suffered from more sleep irregularities.
significant - serotonin regulates sleep patterns. supports the role of serotonin in reactive aggression.

Question 11

hormonal mechanism of aggression - what role does testosterone have in males

Answer 11

men generally more aggressive then women. attention focused on male sex hormone testosterone responsible for the development of masculine features.
also has role in regulating social behaviour via its influence on certain areas of the brain implicated in aggression.

Question 12

animal studies in relation to hormones for aggression + researcher:

Answer 12

Giammonco et all 2005
demonstrated experimental increases in testosterone are related to greater aggressive behaviour in several species.

Question 13

hormonal mechanisms in aggression
test one studies: prison offenders research + researcher

Answer 13

Violent offenders: Married Dolan et al
found a positive correlation between testosterone levels + aggressive behaviours in sample of 60 male offenders in UK maximum security hospitals.
Most these men suffered from personality disorders like psychopathy + had history of impulsively violent behaviour.

Question 14

Evaluation of neural mechanisms in aggression

Answer 14

• alternative explanations:
  Emil coccaro et al (2007) patients with psychiatric disorders the prominent feature of aggression, activity in the OFC is reduced, disrupting its impulsive control function + leading to increased aggression.
  Gospic et al (2011) indicated that aggression the regulation of aggression involved 3 neural structures in the brain: the amygdala, OFC + connection between the two.

-research support:
Mitchell German et al (2009): effects of drugs on serotonin. gave ps placebo drug or dose of paroxetine (enhances serotonin). P then took part in lab based game which gave electric shock varying in intensity.
Paroxetine group gave fewer + less intense shocks than placebo group.
however only true for those with history of aggression. Means- gave useful evidence of link between serotonin function + aggression goes beyond usual correlational findings.

Question 15

evaluation of hormonal mechanisms of aggression

Answer 15

-research support
Allan Mazur formulated biosocial model of status (BMoS) explains link between test + aggression in humans.T levels change rapidly during day especially repsonse to social interactions related to status (competition). CHange in test levels following loss of status should affect post-competition aggression.

-further research support
evidence of link with T + aggression in humans is mixed.
Carre + Mehtas dual hormone hypothesis
claims high levels of cortisol are low. when C is high testorone levels blocked.
C is glucoocorticoid hormone that plays central role in stress response.
Popma study supports this
Comined activity of test and cortisol may be better predictor of human aggression than either hormone alone.