Methods for Studying Brain Function

• post mortem examination AO1

  • invasive
  • the brain can be studied in high detail
  • to look for evidence of brain abnormalities and compare to behaviour from when they were alive
  • early example of this is Broca and patient Tan.
  • high spatial resolution, no temporal resolution
  • is retrospective
• post mortem examination AO3

  • allows the brain to be studied at high levels of detail
  • you dont know when the brain abnormality may have occured. difficult to establish cause and effect between abnormality and the behaviour being investigated.
  • difficult to control extraneous/confounding variables (such as medication and treatment), which can make it more difficult to establish a cause and effect relationship.
  • informed consent - some patients lose the ability to give consent during their lifetime and consent can be a sensitive subject for family members
• fMRI AO1

  • functional magnetic resonance imaging
  • measures changes in brain activity by looking at changes in blood flow across different regions of the brain
  • non-invasive and indirect way to look at brain activity and can be done while an action is being completed
  • has ok spatial resolution (worse than post mortem) and ok temporal resolution (worse than EEGs and ERPs)
• fMRI AO3

  • can be used in real world settings (such as with schizophrenia and sleep disorder patients) to identify which parts of the brain may be related to the disorder
  • doesnt use a radioactive tracer (like PET scans do), so its risk free
  • requires patients to stay still for a clear image, which may not be possible for some patients
  • an indirect measure. studies blood flow changes rather than actual electric neuronal activity. this causes a 5 second time delay between neuron firing and blood flow. (poor temporal resolution) and so may lack validity as a measure of neuronal activity
• EEG AO1

  • electrocephalogram
  • directly measures electrical activity in the brain
  • electrodes placed on the scalp to measure activity from neurons on the cortex which produces a pattern of waves to represent different levels of arousal or consciousness
  • can be used to detect disorders such as epilepsy or alzheimers
  • non-invasive and cheaper to carry out than fMRI scans
  • good temporal resolution, poor spatial resolution
• EEG AO3

  • useful in investigating epilepsy and sleep disorders
  • high temporal resolution (can detect activity in under one millisecond)
  • EEGs only give a general measure. the signal from an individual neuron deep within the brain may not be detected, but signals from a larger area of the brain where many neurons are firing can be detected.
  • abnormal EEGs have been identified in patients suffering with eating disorders such as anorexia nervosa, meaning that EEGs have the potential to be used as a diagnostic tool.
• ERP AO1

  • event related potentials
  • looking at how EEG wave patterns average and change in response to a specific stimulus.
• ERP AO3

  • ERPs have been used in memory research as they give researchers more clues about information processing in the brain
  • cant tell which neurons generated the signal
  • can only look at signals generated by the cortex
• spatial resolution is the level of detail at which the methods allow us to study the brain. highest to lowest:

  • post mortem
  • fMRI
  • EEGs and ERPs
• temporal resolution is the precision of measurements with respect to time

  highest to lowest:

  • EEGs and ERPs
  • fMRI
  • (post mortem examinations do not have any temporal validity)