brain scanning techniques (rm)

• CAT scans AO1

  . a scanner slowly rotates around person, x rays and multiple beams pass into body

  . information gathered is interpreted by a computer

  . detailed cross section images are produced

  . useful for detecting brain damage and finding position of tumors, doesn't give info on brain functioning
• CAT scans AO3 strengths

  . provides higher detail images than normal x rays

  . quick to conduct

  . helps surgeons plan procedures before surgery = faster and more efficient procedure
• CAT scans AO3 weaknesses

  . requires more radiation than normal x rays = can't be used often

  . only provides structural info = limited use in research linking brain activity to behaviour
• PET scans AO1

  . patient injected with small amount of radioactive material - tracer

  . once absorbed into blood stream a continuous performance task is given to stimulate brain and encourage activity

  . as brain works tracer is used up as energy in brain and emits positrons

  . this creates gamma rays which the scanner picks up

  . coloured image produced - red and warm = high activity, blue and cool = low activity
• PET scans AO3 strength

  . shows brain in action = useful for psychologist research

  . can indicate specific areas of brain that are involved in experiences
• PET scans AO3 weaknesses

  . results can be difficult to interpret = difficult to draw conclusions

  . precise location of active areas in relation to brain structure is difficult to pinpoint

  . are ethical issues - injecting substances that can damage tissue

  . expensive to use
• fMRI scans

  . brain activity is associated with blood flow in the brain - this activity is used to gather info and produce image

  . head placed in scanner (large powerful electromagnet)

  . inside magnetic field the nuclei within H atoms in water align themselves with direction of magnetic field

  . as neural activity in brain increases, blood flow also increases to keep up with O2 demands

  . O2 carried in Hb which repels a magnetic field but when deoxygenated it follows direction of field - these changes are detected to make image

  . scanner sends info to computer, generates map of activation
• fMRI scans AO3 strengths

  . shows info on which brain areas are used when

  . does not use radiation = safer

  . non invasive

  . produces very clear images
• fMRI scans AO3 weakness

  . expensive to use

  . only effective if person stays perfectly still = issue in children

  . 5 second time lag between brain activity and image = difficult to interpret info

  . high power magnetic fields = some people can't use eg with pacemakers
• brain scanning used in studies

  . Raine - used PET scans to compare brains of murderers and non murderers

  . Montay - used fMRI scans, found gamers showed lower levels of brain activity in recognition to pictures with negative emotion than a control group