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3.2.3 other research methods Flashcards

1
Q

What are the 3 types of scans?

A

PET, CAT, MRI

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2
Q

What are the 2 main categories of brain scans?

A

-structural (shows detail of brain structure)
-functional (records brain activity)

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3
Q

How do PET scans work?

A

-patient injected with radioactive material and with ‘fluorodeoxyglucose’
(a tracer that attaches to glucose)
-tracer absorbed by blood, patient does brain stimulating task, glucose is used up and radioactive atoms start to break down emitting positrons so gamma rays are produced and detected

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4
Q

What can PET scans show?

A

-high gamma ray concentration means lots of glucose has been used up there so there’s high activity, warm colours show high activity
-can detect damaged areas by abnormal activity levels and guess what issues an individual may face

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5
Q

example research of PET scans

A

Raine et al investigated differences between brains of murderers and non murderers and could map abnormal activity in brain regions associated with risk taking and impulsivity

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6
Q

strengths of PET scans

A

-low risk due to very low levels of radioactive substance involved
-objective interpretation with red/blue colour scale

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7
Q

weaknesses of PET scans

A

-more invasive than other techniques as patient is injected
-unadvisable unless absolutely necessary as long term effects are unclear
-expensive

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8
Q

How do CAT scans work?

A

-xrays passed into head from multiple different directions to provide more info
-computer interprets info and creates detailed image of brain structure

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9
Q

What can CAT scans show?

A

useful for detecting areas of brain damage or tumours

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10
Q

Example research of CAT scan

A

Lusins et al studied alcoholism’s effect on cerebral atrophy and found problem drinking was most significant in patients with the condition

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11
Q

Strengths of CAT scan

A

-less risky than exploratory surgery
-quick to conduct
-can give accurate detail on brain structure and help decide/ plan surgery
-efficiency reduces risks associated with being under anaesthetic for a long time

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12
Q

Weaknesses of CAT scan

A

-does not give info on how brain is functioning
-xrays can cause risk as they involve exposure to radiation
-possible benefits of diagnosis must outweigh potential risks
-xray exposure can cause damage to new born babies so pregnant women must avoid

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13
Q

How do MRI scans work?

A

-patient’s head placed in large electromagnet and nuclei in hydrogen molecules in water align themselves with direction of magnetic field
-neural activity and therefore oxygen demand and therefore blood flow increase
-when haemoglobin is oxygenated it repels a magnetic filed, when it’s deoxygenated it follows magnetic field
-these changes are detected by scanner and sent to computer which can create map on levels of neural activity in different parts of brain during a task

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14
Q

What can MRI scans show?

A

images of brain activity without use of radiation and instead by measuring blood flow

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15
Q

Example research of MRI scan

A

Matties et al measured volume of amygdala and aggression and found smaller amygdala correlated with more aggression
-MRI scans can help us find where aggression is in brain

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16
Q

Strengths of MRI scans

A

-relatively safe as there’s no radiation
-non invasive

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17
Q

Weakness of MRI scans

A

-high magnetic fields mean not everyone can have MRI scan eg, anyone with pacemaker
-patients who dislike small spaces/loud noises may become quite distressed

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18
Q

Genotype definition

A

Organism’s complete set of genes, genetic constitution

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19
Q

Phenotype definition

A

observable physical properties of organism due to interaction between genes and environment eg. hair colour

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20
Q

What is the genome?

A

all the genes in a cell, around 20000-25000 in human genome

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21
Q

Where do your genes come from?

A

-23 chromosomes from each parent (forming 23 pairs)
-genes along each chromosome with one from mother and one from father

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22
Q

What is a dominant gene?

A

the stronger gene’s instruction are carried out and it is displayed physically

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23
Q

What is a recessive gene?

A

gene from other parent, is still present but instructions aren’t carried out

24
Q

What does it mean to be a carrier of a gene?

A

still possess a gene but don’t display it but still have the potential to pass it on to offspring

25
What gene causes female versus male?
female : XX pair male: XY pair
26
What is the idea of 'nature' (nature vs nurture)
biological causes for behaviour (influence of genes)
27
What is the idea of 'nurture' (nature vs nurture)
environmental causes of behaviour (eg upbringing)
28
What are the 2 types of twins?
monozygotic (identical), dyzygotic (non identical)
29
How much of their genes do the 2 types of twins share?
MZ: 100% DZ: 50% (like any sibling)
30
What are MZ twins versus DZ twins?
-MZ: born from 1 egg and 1 sperm (2 embryos) so any characteristics that are genetic, they will both inherit -DZ: 2 fertilised eggs from 2 sperm, share genetic characteristics to a certain extent
31
How can twin studies be used?
-twins always have same shared environment but depending on the type of twin, they may not share all DNA so researchers can work out what factors are genetic
32
What factor would explain any differences between MZ twins?
non shared environment
33
What is a concordance rate?
states the rate of agreement between 2 variables (the two siblings)
34
If a behaviour is genetic what is the expected concordance rate between MZ vs DZ twins
higher concordance between MZ as they share the same genes
35
Gottesman and Shields procedure
-researchers assigned each twins pair to MZ or DZ condition (one twin was schizophrenic) -mental health measured by range of tests (hospital notes, questionnaires, interviews atc) -supposedly healthy twins given rank of health/mental illness -researchers calculated percentage of twins who fell into each category
36
Findings of Gottesman and Shields
-for MZ twins, if one was schizophrenic, the other had 50% chance of also being -the other MZ twin usually had some form of disturbance eg hallucinations -for DZ twins, if one was schizophrenic, the other had 15% chance of also being
37
Strengths of Gottesman and Shields
-high ethics as mostly adults who gave informed consent, parents of teens were heavily involved, presumptive consent given for mentally ill, end justifies means -high construct and concurrent validity as their findings agree with earlier research and Rosenthal's theory of the diathesis-stress model of schizophrenia
38
Weaknesses of Gottesman and Shields
-low generalisability as twins are already unusual and are treated differently, many ppts had trauma from WW2 -low reliability as DNA testing was not used to assess zygosity and schizophrenia classification has changed 4 times since this study
39
Application of Gottesman and Shields
Makes people with schizophrenic family aware that they have a biological predisposition to the illness so they can avoid triggers and be monitored for harmfulness
40
Briefly explain the Jim twins
-identical twins who were separated as babies and reunited at 39 -bizarre coincidences between their lives eg. favourite beer, drove chevrolet, nail biters, similar IG and personality -concludes that genes are just as important as environmental influences in shaping personality, structures in brain determines behaviour
41
Evaluate twin studies (strengths)
-high validity as there's natural control over extraneous factors of environment as the twins grow up together -give useful genetic insight when comparing unique MZ and DV twins to discover environmental and genetic influence
42
Evaluate twin studies (weaknesses)
-limited generalisability as twins aren't very representative (1.5% of UK births) and we don't fully understand them, they also live unusual lives with lots of attention and may be mistaken for one another -low validity as we assume genetic similarity in MZ leads to high concordance rates, but it could be due to greater environmental similarity (identical and same sex)
43
Application of twin studies
-clinical applications with practical relevance to medical fields -can help identify trends in families and DNA testing can be used to try and isolate relevant genes, leading to early intervention
44
Why are adoption studies useful?
observing concordance rates between biological parent and child by removing environment in common
45
Evaluate adoption studies (strengths)
-control for the environment as a confounding variable because the child will have a different one to their biological parent so any similarities are due to genetics -longitudinal method allows trends in behaviour to be studied and linked to genetic influences
46
Evaluate adoption studies (weaknesses)
-low generalisability as only certain types of families are accepted as adopters and are likely to be similar to other adopting families, and to biological families which makes them less representative -worry that adoption studies may create rift in family, between step siblings or biological families as they cause 'self doubt' which the BPS warn about- debriefing required
47
aim of Heston's adoption study
see how many children of biological mothers with schizophrenia would develop it themselves
48
sample of Heston's study
47 subjects born to hospitalized mothers in Oregon and adopted at birth, with fathers of no known hospitalisation
49
control group of Heston's study
-matched group of 50 adoptees whose mothers were believed to be mentally healthy -matched for sex, type of eventual placement and length of time in child care -necessary to eliminate possibility that adoption causes schizophrenia
50
sampling technique used in Heston's study
subjects contacted by letter and asked to participate in a personal standardized interview
51
procedure of Heston's study
standardized interview at subjects' homes, both medical and environmental, all promising leads were followed,
52
What was the rationale behind Heston's study?
-if schizophrenia is not genetic then very few children will develop their mother's condition -if schizophrenia is genetic then about 10% of the children would develop their mother's condition
53
results of Heston's study
-10% of adopted children developed schizophrenia (5 hospitalised, 3 chronically ill) -0 of control group developed schizophrenia -diagnosis of schizophrenia by 3 raters who judged info on each subject, psychiatric hospitals
54
Conclusion of Heston's study
powerful evidence for roles of genes in schizophrenia, no evidence for role of environment in developing schizophrenia
55
Evaluate Heston's study (strengths)
-high reliability due to standardised interviews, good agreement between 3 raters and evaluator who was blind to hypothesis -high validity as matched pairs design used based on sex, time in childcare and eventual placement so meaningful comparisons can be made
56
Evaluate Heston's study (weaknesses)
-low generalisability as volunteer sample was used which means they have shared characteristics -low validity due to use of interviews which may lead to desired characteristics

PSYCHOLOGY Bio (11 decks)

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