Ways of investigating the brain

• fMRI


  • measures changes in brain activity while a person performs a task.
  • it does this measuring changes in blood flow in particular areas of the brain which indicates increased neural activity
• EEG


  • measures electrical activity in the brain.
  • electrodes placed on scalp detect small electrical changes from activity of brain cells.
  • signals are graphed over a period of time
• what has EEGs helped us understand more

  Epilepsy and Alzheimer disease
• ERPs


  • very small voltage changes in the brain which are triggered by a specific stimulus.
  • it requires many presentations of the stimulus
  • then the responses are averaged together
• post mortem


  • used to correlate behaviour after death to see if the patients behaviour during life was due to abnormal brain activity
• fMRI strengths


  • not invasive, doesn't rely on radiation
  • produces clear spatial resolution
  • clear images of how brain is localised
• fMRI weaknesses


  • expensive
  • only works if patient stays completely still
  • poor temporal resolution due to 5 second time lag
  • not a direct measure of neural activity
• EEG strength


  • high temporal resolution
  • very helpful in epilepsy and sleep pattern research
• EEG weaknesses


  • cannot identify specific source of neural activity
  • researchers cannot distinguish between activities originating in different but adjacent areas of the brain
• ERP strengths

  • high temporal resolution
  • provide a continuous measure of processing in response to a stimulus
  • understanding of cognitive function eg working memory
• ERP weaknesses

  • lack of standardisation which can be hard when confirming findings
  • background noise has to be eliminated which may not be easy to achieve
• post mortem strengths

  • provides early understanding of processes in the brain eg Borca and Wernicke
  • improve medical knowledge
  • help generalise hypothesis for further studies
• post mortem weaknesses

  • observation in the brain may not be linked to cognitive function (cannot establish causation)
  • informed consent eg if you've lost your memory you may not be able to provide informed consent