Other Biological Research Methods Flashcards
what does CAT scan stand for ?
computerised tomography scan
what is a CAT scan ?
1) X-rays and computer create detailed structural images of body/brain
2) a large doughnut-shaped scanner rotates around an individual
3) each image is a cross-section of body/brain combined to form detailed picture
what is a positive of CAT scans ?
reveals abnormal brain structures (e.g. tumours) - image quality is much higher than that of traditional X-rays
what are two negatives of CAT scans ?
1) needs more radiation than traditional X-rays - more detailed/complex the scan, the more radiation exposure (cannot be used often)
2) only provides information about brain structure - still images, not ‘live’ brain activity (unlike PET or fMRI), so unlimited use in research
what does PET scan stand for ?
Positron emmission tomography scan
what is a PET scan ?
1) measures metabolic activity in the brain (i.e. most active areas)
2) injection of a small amount of radio tracer (e.g. radioactive glucose) - the most active areas use more of it
3) most active areas coloured red or yellow on the scan, least active areas represented as blue
what are two positives of PET scans ?
1) shows the ‘live’ brain in action - useful in research, links biological activity to behaviour
2) shows specific brain areas linked to experience - evidence of localisation of function (e.g. identifies brain areas linked to thinking about something)
what are two negatives of PET scans ?
1) sometimes the results are not easy to interpret - e.g. different people doing same task show different brain activity - hard to draw conclusions
2) ethical issue (injection of radioactive glucose) - radio tracers can cause tissue damage, so used just once every six months (limited usefulness)
what does fMRI scan stand for ?
functional magnetic resonance imaging scan
what is a fMRI scan ?
1) radio-waves measure blood oxygen levels in the brain (most active areas use most oxygen so blood is directed to these areas - haemodynamic response)
2) activity picked up through radio signals which produce a series of images of successive ‘slices’ turned into a 3D image by a computer
what are three positives of fMRI scans ?
1) shows which areas of the brain are being used - e.g. Pardini et al. related amygdala volume to observed levels of aggression
2) does not use radiation - makes it safer than PET scans and CAT scans
3) fMRI images very clear - can show brain activity to the millimetre
what are two negatives of fMRI scans ?
1) person has to stay perfectly still in the scanner - difficult for some (e.g. children), so limits the use of fMRI scans with some kinds of research
2) 5 second delay between brain activity and image - can cause problems trying to interpret the information
