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OUTLINE THE GENETIC EXPLANATION OF AGGRESSIVE BEHAVIOUR. 20 MARKS

Neuro explanation

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Biological Explanations of aggression

Outline the Genetic explanation of Aggressive behaviour.20 marks

A01Aggression is HereditaryGenetic Mutations (XYY)Inter-breeding in Animal Studies with aggressive phenotypesResearched with twin studies (Mz vs. Dz to discover concordance rates)Researched in Adoption Studies with violent histories in biological parents but not adoptive parents

A02Twin studies concordance rating(Mason & Frick) 48% genetic Adoption studies(Hutchings & Mednick) Denmark 14000 adoptions, significant positive correlation only between bio. Parents and child.Case Studies (Brunner) MAOA & (Sandbarg) XYY Animal Studies(Lagerspetz) Aggressive mice interbred, 19th generation more aggressive

AO3

GenderReductionistEthical Guidelines?Nature vs. NurtureAnimal StudiesDeterminsm vs. Free WillEthnocentricism

4

Biological Explanations of aggressionNeural anatomyNeural chemistryPlan 24 mark on Neural explanations of aggression

Can anyone explain what these are? (class discussion hands up activity) Then go through and explain each. Then get them to link these to aggression, very basically e.g. Might be a gene that causes aggression, does anyone know any hormones that might explain it?6

Neurotransmitterschemicals which allow the transmission of signals from one neuron to the next across synapses

Neurotransmitters what we already knowDecreased levels of Serotonin Enzymes = Increased Aggression

Warrior Gene

HoweverHigher levels of serotonin may not be the whole story

NeurotransmittersSerotonin has a relaxation function

It inhibits aggressive behaviour

Neurotransmitters what we already knowDecreased levels of Serotonin Enzymes = Increased Aggression

Warrior Gene

Low levels of SerotoninAggressionImpulsive BehaviourViolent SuicideDepressionAlcohol AbuseOver eating

Low levels of Serotonin can lead to an increase in aggression

Serotonin inhibits our response to emotional stimuli that can lead to aggressive behaviour

Reduced Serotonin = Reduced ability to control aggressive impulses

Low levels of SerotoninAlcohol and Aggression

Increased alcohol consumption is often positively correlated with aggression

Alcohol causes a decrease in Serotonin levels

The reduction in Serotonin stops inhibition of aggressive behaviour

Low levels of serotoninHigley (1996)

Free-ranging, male, rhesus monkeys

Higley (1996) Monkeys Serotonin levels were measured

Those with the lowest Serotonin were more likely toFightHave more scars and woundsPick fights with larger opponentsJump from trees higher than 7 metres

Serotonin & Drug therapy Drugs that decrease levels of Serotonin can be used for weight control

Drugs that increase levels of Serotonin can be used to treat depression (Prozac)

Mann et al (1990)

Drug Dexfenfluramine reduces appetite by reducing Serotonin

The drug was given to 35 healthy participants

Questionnaire was given to all pps to assess hostility before & after treatment

Mann et al (1990)

Results showed that male pps were more hostile after taking the drug

This result was not found in females.

Serotonin & Drug therapy Bond (2005)

Prozac is an anti-depressant which increases Serotonin

Individuals who take Prozac experience reduced impulsive aggressive behaviour

Mann et al (1996)Violent suicide associated with lower levels of Serotonin

Low serotonin & criminal behaviourDavidson et al (2000)

Criminals with more violent history of criminality had markedly lower levels of Serotonin compared with non-violent criminals.

NeurotransmittersAggression is linked to

Low levels of Serotonin High levels of Dopamine

DopamineDopamine and Aggression link is much less well established than Serotonin

There is some evidence of a link between high levels of Dopamine and an increase in Aggressive Behaviour

DopamineProduced in response to rewarding stimuli

Food SexRecreational Drugs

Couppis et al (2008)

Dopamine plays reinforcing role in aggression

Some individuals seek out aggressive encounters because of the rewarding sensations they provide caused by an increase in Dopamine

Dopamine & Drug TreatmentAmphetamines increase Dopamine levels

Research has found an increase in Aggressive behaviour by individuals under the influence of Amphetamines(Lavine, 1997)

Dopamine & Drug TreatmentAnti-psychotics reduce Dopamine

When violent delinquents are given these anti-psychotics, aggression is reduced. (Buitelaar, 2003)

Conclusion of Neurochemistry & AggressionEvidence for the dual role of Serotonin and Dopamine has been found in Animal Studies

Ferrari et al (2003)Allowed rats to fight every day for 10 days

On the 11th day, it was not allowed to fight and its serotonin and dopamine levels were measured

In anticipation of a fight, the rats Dopamine levels had increased and Serotonin levels had decreased

AO3

GenderReductionistEthical Guidelines?Nature vs. NurtureAnimal StudiesDeterminsm vs. Free WillEthnocentricism

32

Can anyone explain what these are? (class discussion hands up activity) Then go through and explain each. Then get them to link these to aggression, very basically e.g. Might be a gene that causes aggression, does anyone know any hormones that might explain it?33

Neural Anatomy (Brain Structure) & AggressionAre aggressive brains structurally different to non-aggressive brains?

Pre-Frontal CortexHypothalamusAmygdala

Hypothalamus Controls hormone release

Regulates:TemperatureThirst/HungerSleepMoodSex Drive

Hypothalamus Siegel & Pott (1988)Research with cats

Activation of the hypothalamus causes aggressive response and vicious attack behaviour

AmygdalaEmotion centre

Emotional ResponseAutonomic resoponse to fearMemory

Amygdala & AggressionPotegal (1996)Direct Stimulation of Amygdala causes Aggressive behaviour in Hamsters

The Amygdala remains active half an hour after violent attackRed Alert

Amygdala & AggressionPotegal (1996)

Also found heightened Amygdala activity 5-20 mins after aggressive provocation in humans

Pre-Frontal Cortex (PFC) Higher level CognitionDecision Making

Pre Frontal Cortex & AggressionCase of Phineas Gage

Personality became more impulsive and aggressive following injury to PFC

Pre Frontal Cortex & AggressionRaine et al (1997)

PET scans of 41 murders compared to matched controls

Murderers had significantly lower levels of activation in the PFC

Outline Neural Explanations of Aggression(20 marks)A01 Outline NT effects (Sr & Dp) & outline neural structures (Hp, Am & PFC)

A02 Evaluate with studies Animal Studies, Drug therapy, Case studies

A03 Reductionist; Nature not Nurture; Animal Studies; Deterministic