Explanation For Aggression: Brain Structure And Functioning

Question 1

Bio explanations for aggression:
Brain Functioning and aggression

P.E.E paragraph- Amygdala strength

Answer 1

The amygdala controls our perception of emotion eg anger, helping store memories of events/ emotions to recall when similar events occur. It is thought damage to this area could lead to aggressive behaviour due to lack of emotional response surrounding violent actions and failure to learn from criminal behaviour. Raine’s 1997 study of murderers and non murderers using PET scans supports this, as he found significant reduction of glucose metabolism in the left and greater right amygdala in murderers, suggesting that amygdala abnormalities could lead to aggressive behaviour.

Question 2

Bio explanations for aggression:
Brain Functioning and aggression

P.E.E paragraph- Amygdala + PFC weakness

Answer 2

Furthermore, interaction between the amygdala and pre frontal cortex (PFC) have been suggested to link to aggression, with the PFC acting on the lateral nucleus of the amygdala and suppress the conditioned fear response, suggesting those acting aggressively do so out of lack of fear. However, evidence for the link between aggression, the amygdala and PFC from Raine can be criticised as lacking validity. Raine is only able to make a correlation, not causation between the murderers and lower glucose metabolism in these parts of the brain as we are unable to establish when these brain abnormalities occurred, for instance it could be as a result of the murders not a cause. Therefore, demonstrating a lack of validity as a cause and effect conclusion cannot be made.

Question 3

Bio explanations for aggression:
Brain Functioning and aggression

P.E.E paragraph- PFC strength

Answer 3

The damage to the pre frontal cortex, controlling personality, planning, emotional response and social inhibitions is said to be linked to aggression through loss of self control, altered emotionality and impulsivity all leading to aggressive behaviour. This is strengthened by the case study of Phineas Gage who after damage to his frontal and pre frontal lobe, had a complete change in personality from someone responsible, intelligent and well liked to irreverent, impulsive and speaking obsenely. Suggesting our PFC has strong ties to our personalities and aggressive responses.

Question 4

Bio explanations for aggression:
Brain Functioning and aggression

P.E.E paragraph- Males and PFC Weakness

Answer 4

Aggressive and implusive acts are more associated with and mostly seen in young males, explained by the PFC which only fully develops at early to mid 20s, as boys through more rough activities than females are more likely to damage their developing PFC, leading to more aggressive and implusive tendicies. However, there are alternative explanations for aggression, opposing the nature focused biological explanation. Social learning theory would state aggression is as a result of observing and imitating aggressive role models such as a same sex parent.Showing that the biological explanation fails to account for environmental factors and so is reductionist.

Question 5

Bio explanations for aggression:
Brain Functioning and aggression

P.E.E paragraph- Nature vs Nurture conclusion

Answer 5

In conclusion, both sides the nature- biological and nurture - environmental debate offer explanations for aggression. As aggression, like most human behaviour is a complex behaviour, it is unlikely to be caused by just on factor. Therefore, it is likely that aggressive behaviour is caused by an interaction of biological and environmental causes.

Question 6

Bio explanations for aggression:
Brain Functioning and aggression

A01- Brain Lobes

Answer 6

Brain Lobes:

• Temporal lobe: Memory, understanding language, facial recognition, hearing, vision, speech, emotion
• Occiptial lobe: Vision, visual processing, colour identification
• Parietal Lobe: Perception, object classification, spelling, knowledge of numbers, visuospatial processing
• Cerebellum: Gross and fine motor skills, hand eye co-ordination, balance
• Frontal/ pre frontal lobe: One of the 4 main lobes/regions of cerebral cortex. At the front of the cerebral cortex, involved in movement, decision making, problem solving, planning. Pre frontal cortex (part of FL) is responsible for personality, expression and planning of complex cognitive behaviours. Is said to contain our personalities, has input into our emotional responses and control of our social inhibitions. Acts as ‘voice of reason’- guiding humans to make rational decisions vs impulsive ones. Develops slowly= full maturity early-mid 20s. Linked to aggression eg Phineas Gage. Also implicated in depression and regulating emotions
• Limbic system: Complex set of structures; hypothalamus, hippocampus, amygdala etc associated with emotional processing and behaviour

Question 7

Bio explanations for aggression:
Brain Functioning and aggression

A01- Amygdala

Answer 7

Amygdala: Responsible for perception of emotions(anger, fear, sadness) and controlling aggression. Helps store memories of events+ emotions- recognise similar events in future. Size is positively correlated with increased aggression and physical behaviour. Found animals can be tamed through lesions to amygdala

• Plays a role in recognition of affective and socially significant stimuli- destruction of amygdala causing lack of fear in a animal, in man reduced autonomic arousal
• These abnormalities in amygdala relevant to aggression= reduces autonomic arousal in humans- fearlessness and reduction in emotional response

Question 8

Bio explanations for aggression:
Brain Functioning and aggression

A01 + A03- Hypothalamus

Answer 8

Hypothalamus: Responsible for production of essential hormones- chemical substances help control different cells and organs. These hormones govern physiological functions eg temp regulation, thirst, hunger, sleep, mood, sex drive, release of other hormones. Contains pituitary gland as well as other glands
Evidence: A03
Alper’s (1937)-Human
- Studied a well-liked mild-mannered, middle aged lawyer who was later found to have a tumour in the medial hypothalamus- began displaying uncharacteristic outbursts of aggressive behaviour= shocking to all that knew him- tumour thought to be cause

Hess(1928)-Animal
- Demonstrated ability to induce aggressive behaviour in cats through electrical stimulation of hypothalamus. Hypothalmic attack area simulated in medio-basal hypothalamus in rats and cats= ‘biting attacks’. Similar structures in human brains exist in PFC- which damage to is linked to human aggression

Question 9

Bio explanations for aggression:
Brain Functioning and aggression

A01- Lateralisation

Answer 9

Lateralisation=

• Some structures across the 2 hemispheres- bilateral
• Joined by Corpus Callosum- passes messages between 2 hemispheres= if communication system is damaged- they can’t work together
• Splits corpus callosum= no communication between 2 hemispheres
• Corpus callosum = Largest white matter structure in the brain, function to connect grey areas together with neural impulses. Also communicates to cerebral cortex, subcortical structures, thalamus, hypothalamus