EEG - Electroencephalograph

• • Electroencephalgram measures electrical activity in the brain.
  • Electrodes placed on scalp detect small electrical charges in form of action potentials resulting from activity of brain cells
  • electrical signals from different electrodes are graphed over a period of time, resulting representation called an EEG
• amplitude


  intensity or size of the activity
• Frequency


  speed or quantity of activity
• EEG's 2 distinctive patterns

  • synchronised - recognisable patterns (alpha, beta, theta, delta)
  • desynchronised - no patterns
• 4 types of EEG waves

  • Alpha - light sleep/relaxed state
  • Beta - awake state
  • Theta - relaxed/light sleep
  • Delta - progressively deeper sleep
• EEG waves can be used to detect various types of brain disorder or to diagnose other disorders that influence brain activity. EEG patterns in patients with brain disease and brain injury show overall slowing of electrical activity.
• A03 Positive

  • EEGs have proven practical use in healthcare
  • EEG data can be used to detect various types of brain disorder or to diagnose other disorders that influence brain activity.
  • e.g EEG readings of patients with epilepsy shown spikes of electrical activity
  • EEG patterns in patients with brain disease and brain injury show overall slowing of electrical activity
• A03 Negative

  • EEG signal cannot pinpoint source of neural activity in the brain - researcher cannot distinguish between activities originating from different but nearby areas in the brain (poor spatial resolution) - both only detect activity in superficial general areas of brain.