Ways of studying the brain

• psychologists use medical techniques to investigate brain localisation
• techniques for investigating the brain are often used for medial purposes in the diagnosis of illness.

  the purpose of scanning in psychological research is often to investigate localisation- to determine what parts of the brain do what
• fMRI= highlights active areas of the brain
• fMRI:

  functional magnetic resonance imaging detects changes in blood oxygenation and flow that occur due to neural activity in specific brain areas

  when a brain area is more active it consumes more oxygen and blood flow os directed to the active area (haemodynamic response)

  fMRI produces a 3D image showing which parts of the brain are active and therefore must be involved in particular mental processes
• EEG= shows overall electrical activity
• EEG:

  electroencephalogram measures electrical activity within the brain via electrodes using a skull cap

  the scan recording represents the brainwave patterns generated from millions of neutrons. this shows overall brain activity

  EEG is often used as a diagnostic tool. for example unusual arrhythmic patterns of brain activity may indicate abnormalities such as epilepsy, tumours or sleep disorders
• ERPs= brainwaves related to particular events
• ERPS:

  event-related potentials are what is left when all extraneous brain activity from an EEG recording is filtered out

  this is done using a statistical technique, leaving only those responses that relate to the presentation of a specific stimulus or performance of a certain task

  ERPs are types of brainwave that are triggered by particular events

  research has revealed many different forms of ERP and how these are linked to cognitive processes (e.g. perception and attention)
• Post-mortem examinations:

  a technique involving the analysis of a persons brain following their death

  areas of the brain are examined to establish the likely cause of a deficit or disorder that the person suffered in life

  this may also involve comparison with a neurotypical brain in order to assess the extent of the difference
• strength of fMRI:

  unlike other scanning techniques (e.g. PET), fMRI doesn't reply on the use of radiation and is safe. another strength is it produces images with high spatial resolution, showing detail by the millimetre. this means fMRI can provide a clear picture of how brain activity is localised
• limitation of fMRI:

  fMRI is expensive compared to other techniques and can only capture a clear image if the person stays still. another limitation is it had poor temporal resolution because of 5-second lag between initial neural activity and image. this means fMRI may not truly represent movement-to-movement brain activity
• strength of EEG:

  EEG has also contributed to our understanding of the stages of sleep. another strength is that EEG has extremely high temporal resolution. EEGs can detect brain activity as a resolution of a single millisecond
• limitation of EEG:

  the EEG produces generalised signal from thousands of neurons. another limitation is it's difficult to know the exact source of neural activity. EEG can't distinguish the activity of different but adjacent neurons
• strength of ERPs:

  ERPs are more specific than can be achieved using raw EEG data. another strength is that, like EEGs, ERPs have excelled temporal resolution. this is especially so compared to fMRI, for example.
• limitation of ERPs:

  this makes it difficult to confirm findings in studies involving ERPs. another limitation is that background noise and extraneous material must be completely eliminated. this may not always be easy to achieve
• strength of post-mortems:

  broca and wernicke both relied on post-mortem studies. another strength is post-mortem studies improve medical knowledge. they help generate hypothesis for further study
• limitation of post-mortems:

  observed damage in the brain may not be linked to the deficits under review but to some other related trauma or decay. another limitation is post-mortem studies raise ethical issues of consent from the patient before death. patients may not be able to provide informed consent.