Methods of Studying the Brain

• Non-invasive methods allow us to relate activity in the brain to behaviour but do not involve manipulating the brain, and therefore can’t directly test cause and effect. We can directly test cause and effect relationships between the brain and behaviour using invasive methods.
• What are post-mortem examinations?


  When a person’s brain is examined in detail after-death to look for evidence of brain abnormalities.
• What is one strength of post-mortem examinations?


  In a post-mortem examination, a person’s brain can be examined at a very high level of detail, to identify very small brain abnormalities.
• One weakness of post-mortem examinations is that we don’t know when the brain abnormality occurred making it difficult to establish a cause and effect relationship.
• What is a second limitation of post-mortem examinations?


  It is hard to control confounding, or extraneous variables, like medication, which might also affect the patients’ brains.
• Magnetic Resonance Images

  • MRI scans can’t detect which parts of your brain are generating electrical activity.
  • MRI scans can detect if there is a big hole or tumor in your brain.
• What is fMRI?

  • fMRI stands for functional Magnetic Resonance Imaging.
  • fMRI measures changes in brain activity across the brain.
• How does functional magnetic resonance imaging measure brain activity?


  fMRI measures the changes in blood flow that occur across parts of the brain while people perform tasks. fMRI works because, the more active a brain region is, the more oxygen it needs and so the more blood flows towards that brain region.
• What is one strength of fMRI scanning?


  fMRI allows us to investigate the relationship between activity in the brain, and a person’s behaviour more directly than with post-mortem examinations.
• How does fMRI measure brain activity?


  fMRI measures changes in blood flow that occur as a result of an increased demand for oxygen.
• What are the limitations of fMRI?


  • Can't be sure there is a causal relationship
  • Neural activity is not the only thing affecting blood flow
  • fMRI might not pick up all changes in neural activity (too slow)
• What does EEG stand for?


  Electroencephalogram
• What does Electroencephalography measure?


  Neural activity in the brain
• How do EEG's work?

  • EEG uses electrodes placed on the scalp to pick up electrical activity of neurons located under the electrodes.
  • EEG picks up electrical signals from the cortex
• What are the pros of EEG's?

  • Allows us to measure actual neural activity in the brain, directly
  • Allows us to detect certain types of events in the brain
• What are the strengths of EEGs?


  • EEG is good at detecting synchronised activity that occurs when people sleep or have seizures.
  • EEG can directly measure neural activity generated by neurons in the cortex.
• What are the cons of EEG's?


  • Doesn't give much information about which neurons are generating electrical signals
  • Can only pick up electrical activity from the cortex
  • Hard to interpret because electrical signals detected by electrodes are small