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Biological Psych revision, frontal lobe - fine motor control, judgement,…
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- frontal lobe - fine motor control, judgement, personality, problem solving and decision making
- parietal lobe - 3D manipulation, morality, touch and pain perception, spatial awareness and balance, codes and symbol interpretation
- occipital lobe - 3D balance, vision, damage can cause blindness
- temporal lobe - hearing, memory and language, emotion
- NGRIs showed less activity in the prefrontal cortex (morality) especially where associated with rational thinking, self control and memory
- less activity in parietal lobe associated with abstract thinking - morality and justice but more in the occipital lobe - vision
- in the sub-cortical region, NGRIs saw less activity in the corpus callosum (long term planning)
- imbalance in activity between the left and right hemispheres of the limbic system
- less activity on the left and more on the right in the amygdala and hippocampus
- more activity on the right side of the thalamus
- these areas of the brain are associated with aggression in animals
- concludes that findings from animal studies on aggression can be generalised to humans and that there is a link between brain structure and aggression
- prefrontal deficits may make some people more impulsive and emotional
- deficits in the limbic system might make some more aggressive - seen first in cats where the amygdala controls urges and desires, thalamus processes information and the hippocampus processes memory, deficits make it harder for someone to learn from mistakes or understand their emotions
- deficits in corpus callosum makes it harder for the brains hemispheres to communicate making it difficult to think through long term consequences and make decisions
- areas like the parietal lobe, amygdala, and hippocampus are important to recognition - deficits may make it harder to judge social situations leading them to overreact.
- Acetylcholine - stimulates muscle control and has a key function in fine motor control, also necessary for memory and other cognitive functions like attention and alertness, also involved in expressing emotions such as anger or sexuality
- GABA - an inhibitor in the brain which calms nerves that are firing and prevents relaxation
- Nor-adrenaline - associated with emotion particularly in mood control. involved in functions such as sleeping and dreaming as well as learning
- Dopamine - chemical precursor to nor adrenaline so their functions are similar related to emotion and cognitive function as well as exposure and control of movement. also been associated with reinforcement in learning as well as dependencies. dopamine is used in hormonal regulation such as control of the menstrual cycle
- serotonin - most associated with mood particularly in limbic system. also involved with feeling pain, sleep, regulating body temperature, hunger
- to see if social aggression coould be caused by genes or by environment
- to see if social aggression shared the same cause as physical aggression
- to see if one type of aggression leads to another type
- 234 twin pairs were involved, 44 MZ males, 50 pairs MZ females, 41 pairs DZ males, 32 pairs DZ females, 67 pairs mixed-sex DZ twins - data originally gathered longitudinally at 5, 18,30,48 and 60 months and then at the age of 6 years - this is the data focused on in this study
- Generalisability - large sample of 234 pairs so anomalous children should not have had an affect on the overall results
- sample attrition - 80 pairs disappeared from the quebec study before the 6 year testing point and if some of these were the more disturbed children or those with chaotic backgrounds then the study may not be so representative
- study only looked at six year olds - in some ways this is representative because they are going through the shift from physical to social aggression but still showing signs of both
- in other ways it may not be Representative because some children will develop slowly and others quickly - more mature children may have more non-shared environmental influences
- Reliability - brendgen uses established questionnaires to measure aggression, two researchers visited each classroom - inter-rater reliability.
- a strong correlation between teacher and peer rating suggests the results are reliable
- language differences may make study less reliable, questions translated into another language might have a different meaning or become confusing - original questionnaires were in French
- allocation of zygosity was based largely on appearance and wasn't reliable - there could be DZ twins in the MZ condition
- applications - if social aggression is strongly linked to the environment then it must be possible to reduce the worst effect of bullying and gossiping in social media by early intervention
- if friends and family are a big influence on social aggression it suggests that education for parents on better ways of handling children might prevent the children from being socially aggressive with their own friends
-Validity - twin studies are a valid way of studying nature versus nurture - MZ twins share 100% of genotype but DZ twins no more than 50%, both share the same homelife. therefore if MZ have similar behaviours where DZ twins do not then it is most likely due to genetic similarity
- this is a natural experiment - so cannot show cause and effect, twins may influence eachother
- avoids taking a reductionist view, looks at genetics but also environmental factors and links with findings on aggression from Bandura (claiming it is learned) and Raine (claiming it is due to brain structure)
- correlation does not prove causation - something else could be affecting the results, similar looking twins can be mistaken from one another, teacher and peer ratings could've been influenced by prejudice as both twins were from the same family
- Ethics - the parents of the twins agreed so presumptive consent was given, teachers also agreed, more presumptive consent
study gets children to judge other children - causing issues, if revenge is sought then this goes against the social responsibility of ethical research and might create risk for the children
- when neuron is at rest, the inside is negatively charged relative to the outside
- when the neuron is stimulated, positively charged particles enter, the action potential is initiated and the neuron is depolarised
- after a brief period, some positively charged particles are pushed outside of the neuron and the neuron moves back towards its polarised shape
- the neuron has returned to its original polarised resting state
Neurons
- Dendrites - branches at the top of a neuron that receive messages from other neurons
- Axon - long branch from the cell body that passes electrical impulses to the end of a neuron
- Axon hillock - the area connecting the cell body to the axon
- Myelin sheath - provides electrical insulation for axons and allows impulses to pass along faster
- nodes of Ranvier - gaps between adjacent myelin sheaths
- axon terminals - the end of the axon leading to the terminal buttons
- vesicles - tiny sacs containing molecules of neurotransmitter chemicals
- resting membrane potential - difference in electrical potential on each side of a cell membrane
- excitatory postsynaptic potential - changes in polarisation of a neuron making it less likely to fire an axon potential
- Antenatal exposure to testosterone has an organising effect on the developing brain leading to increased spatial ability and competitive aggression
- also a crucial point immediately following birth where testosterone sensitises certain natural circuits stimulating cell growth in areas of the hypothalamus and amygdala which later sets up the action of testosterone as an adult to affect aggression
- supporting studies come from research on rodents, male rodents will be castrated stopping testosterone production and their behaviour will be compared with control rodents under a variety of conditions including threat and competition for mates
- castrated rodents show little to no aggression but there is differences according to the age of the rodent at the time of castration if their testosterone is replaced
- testosterone influences aggressive behaviour by affecting changes in neurotransmission but this is complex, a modulating effect on aggression is produced by serotonin
- increased activity of serotonergic synapses inhibits aggression and low levels of serotonin will increase it
- Human studies generally support the idea that testosterone and aggression are linked
- T levels increase during the early teens and there is a strong positive correlation with aggressive behaviour and inter-male fighting - correlation does not indicate causality
- there have been cases where convicted sex offenders have been castrated leading to a removal of aggression and loss of sex drive, this seems to support the idea that T is influential in aggressive behaviour but studies lack control groups etc
- Dabbs et al (1995) - took saliva samples of adult male prisoners to test levels of testosterone
- those with higher T levels had a history of violent crime, those with low T levels committed non-violent crimes
- only men were used and only felons - not generalisable
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