research methods: brain scans Flashcards

1
Q

describe how a CAT scan works

A
  • tunnel machine
  • inside of machine rotates and takes x rays at various angles
  • x rays are sent to computer which creates a cross sectional image
  • 30 mins
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2
Q

what is a CAT scan used for?

A
  • providing detailed images of soft tissues and vessels
  • used to diagnose infections and bone fractures
  • pinpoints tumour location
  • monitor treatments
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3
Q

what a strength of CAT scans (validity)?

A

detailed images
- 0.27s temporal resolution
- 0.3-0.6mm spatial resolution
makes them good at detecting changes in physical brain structure - identifying tumours early

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4
Q

what is a strength of CAT scans (reliability)?

A

standardised procedure
- many x rays taken by rotating machine
- cross sectional image composed of these
- same structure shown every time a scan is done
allow to check for consistency

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5
Q

what is a limitation of CAT scans (ethics)?

A
  • uses radiation
  • same amount in 30 mins as 1-3years normal life
  • exposure could cause further issues
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6
Q

what is a limitation of CAT scans (practicality)?

A

affected by movement
pregnant people can’t have

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7
Q

what is a strength of CAT scans (support study)?

A
  • Lusins et al
  • 50 patients with alcoholism
  • 58% had cerebral atrophy which affects brain with decreased tissue size, loss of neurons
  • however, the only significant factor was due to duration of problem drinking
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8
Q

what is a limitation of CAT scans (validity)?

A
  • low ecological
  • correlation
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9
Q

describe how PET scans work

A
  • cylinder tunnel scanner
  • measures metabolic activity
  • fluorodeoxyglucose radiotracer injected into arm
  • 45 mins to reach cells and collect in body, needs time to decay
  • scanner detects radiation
  • most active areas use more (red) less active use less (blue)
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10
Q

what are PET scans used for?

A
  • shows how well parts of the brain are working
  • investigate response to treatment
  • measures blood flow & oxygen use
  • identify brain disorders eg parkinsons or epilepsy
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11
Q

what is a limitation of PET scans (ethics)?

A
  • invasive
  • fluorodeoxyglucose tracer
  • potential tissue damage - exposure to radiation
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12
Q

what is a strength of PET scans (validity)?

A
  • high validity
  • measures what it claims to measure eg speech impairments caused by certain areas of the brain being damaged
  • however, low eco as artificial task
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13
Q

what is a strength of PET scans (reliability)?

A
  • standardised procedure
  • high is red low is blue
  • produces same comparable images interpreted same by all researchers
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14
Q

what is a strength of PET scans (support study)?

A
  • Raine et al
  • discover if there are brain abnormalities in NGRI murderers
  • significant differences eg lower glucose metabolism in PFC
    however correlational
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15
Q

what is a limitation of PET scans (validity)?

A
  • results hard to interpret
  • PET scans on people doing same task show diff brain activity in diff people
  • hard to draw conclusions about which brain areas link to which behaviours
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16
Q

describe how fMRI scans work

A
  • patient performs tasks whilst in scanner eg moving fingers
  • head placed in powerful electromagnet
  • magnetic field inside scanner which is formed between the electromagnet and a nuclei of atoms
  • when neurons become more active, more oxygen is required so blood vessels widen and flow increases which is detected by scanner
17
Q

what are fMRI scans used for?

A
  • shows brain activity
  • identify tumours
  • look for regions that work when using language or checking memory
18
Q

what is a strength of fMRI scans (ethics)?

A
  • no radiation
  • not invasive
19
Q

what is a limitation of fMRI scans (generalisability)?

A
  • no pacemakers
  • no metal implants
20
Q

what is a strength of fMRI scans (support study)?

A
  • Li et al
  • relationship between chronic heroin use and changes in brain function
  • significant difference in activation regions associated with reward system
  • however correlation
21
Q

PET scan resolutions

A

temporal = 5-10 secs
spatial = 4-5mm

22
Q

fMRI scan resolutions

A

temporal = 1-4 secs
spatial = 1-2mm

23
Q

what is a strength of fMRI scans (validity)?

A
  • developed most recently
  • modern and advanced technology
  • most precise - detect smallest changes