Investigating brain

• fMRI

  • a non invasive technique that allows you to see what parts of the brain are working
  • it detects changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain
  • when the brain is more active, it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area
  • fMRI produces 3d images that show what happens
• fMRI - evaluation

  • unlike PET scans, it does not rely on the use of radiation and is usually very safe when administered
  • shows a very clear and detailed picture of the brain and how brain activity is localised
  • it has high spatial resolution meaning that it can show which area of the brain is active whereas EEGs are hard to work out where the wave originates from
  • it is very expensive compared to others
• EEG (electroencephalogram)

  • this measures overall electrical acitivity within the brain via electrodes that are fixed to an individual's scalp using a skull cap
  • electrodes pick up electric signals naturally produced by the brain
  • allows researchers to follow impulses over the surface of the brain and observe changes over split seconds of time
  • often used as a diagnostic tool
• EEG - evaluation

  • useful in diagnosis, e.g. epilepsy
  • has contributed to our understanding in the stages of sleep
  • can accurately detect brain activity at a resolution of a single millisecond compared to fMRI that has a lag of 5 seconds before an image occurs after activity, and therefore can be said to have high temporal resolution
• ERP (event related potential)

  • shows how an EEG wave pattern changes in response to a stimulus
  • EEG data contains all the neural responses assosciated with sensory specific events
  • extraneous data is filtered out and leaves only responses that stimulate to a specific stimulus or task
• ERP- evaluation

  • compared to fMRI it has excellent temporal resolution as it shows activity to a single millisecond compared to a lag of five seconds with an fMRI
  • has been widely used in cognitive functions and deficits
  • has more specifity in the neural processes
  • BUT EEG is not useful to pinpoint the exact source of activity because electrical activity can be picked up by several neighbouring electrodes
• Post mortem

  • an examination of a brain following their death
  • areas of the brain that are damaged can be investigated to establish the cause of the problem
  • a comparison with a neurotypical brain can be drawn
• Post mortem - evaluation

  • can be used to provide a foundation for early processes involved in the brain
  • observed damage in the brain may not be linked to the deficits under review and may be linked to other trauma and is therefore hard to establish causation
  • deeper areas of the brain can be physically studied with post mortems so could look at areas of limbic system such as hypothalamus