exam questions

• Describe how PET scans can be used to investigate brain structure (2)

  -       PET scans use radioactive tracers 

  -       PET scans detect production of gamma rays 

  -       Provides a 3D image.
• Describe the role of visual stimulation on the development of the visual cortex during the critical period (3)

  -       Oscular dominance columns develop in visual cortex

  -       Neurones form synapses with these columns

  -       Action potential along neurones required to strengthen connections with cells of ocular dominance 

  -       Stimulation during critical period needed to form effective connections in the visual cortex.
• FMRIs measure brain activity by?

  -       blood flow 
• Explain how FMRI can be used to identify the part of the brain involved in interpreting information from the visual cortex (3)

  -       FMRI detects blood flow/oxygen use in the brain

  -       Increased brain activity results in increased blood flow due to higher demand of oxygen due to high levels of aerobic respiration in areas of activity 

  -       Oxyhaemoglobin absorbs fewer radio waves so FMRI detects areas where less signal is absorbed
• Describe why a region of the brain might appear lighter in an image obtained by a FMRI scan (3)

  -       Areas more active in the brain require more blood flow due to more oxygen needed for aerobic respiration in these active areas 

  -       Oxyhaemoglobin in the blood absorbs radio waves (FMRI signals) less so these areas appear lighter on the scan 
• Describe why a combined PET and CT scan may be better for diagnosing cancer than these scans on their own (3)

  -       Using both provides info on the function and structure

  -       Ct uses x-rays, dense tissue/tumours absorb more x rays and show up lighter shows’ location and size 

  -       PET scans show areas which are more metabolically active/dividing more

  -       Due to use of x-rays in CT scans, less x rays emitted as a mix of scans used