ways of studying the brain

• post mortem examination

  when a person dies researchers examine brains to look for abnormalities that could explain their behaviour
• fMRI scans

  • measures changes in brain activity while a person performs a task
  • does this by measuring changes in blood flow in particular areas of the brain
• EEG scans

  • measures electrical activity in the brain using electrodes placed on the scalp
  • when the electrical signals are graphed over a period of time, the representation is called an EEG
• ERP scans

  • like an EEG
  • researchers filter out background brain waves to find one brain wave that links to 1 event / stimulus
• post mortem eval - strengths :)

  • PM evidence was vital in providing an early understanding of key processes in the brain
  • broca and wernike relied on PM studies when establishing links between language, brain and behaviour decades before neuroimaging was a possiblity
  • PM studies were also used to study HM's brain to identify areas of damage which could be associated with his memory deficits, meaning PM's continue to provide useful information
• post mortem eval - weaknesses :(

  • causation - observed damage to brain may not be links to deficits but to some other unrelated trauma or decay
  • ethical issues - P's may not be able to provide informed consent (eg. HM who lost ability to form memories wasnt able to provide such consent but research was still conducted on his brain)
  • challenges usefulness in psychological research
• fMRI eval - strengths :)

  • doesnt rely on use of radiation - unlike other (PET), if administered correctly it is virtually risk free, non invasive and straightforward
  • very high spatial recognition - captures details by the millimetre, providing clear picture on how brain activity is localised
  • means an fMRI can safely provide clear picture of brain activity
• fMRI eval - weaknesses :(

  • expensive - compared to other techniques
  • poor temporal resolution - 5 second time lag behind the image on the screen and initial firing of neuronal activity
  • means fMRI may not truly represent moment to moment brain activity
• EEG eval - strengths :)

  • useful in studying stages of sleep and diagnosis of epilepsy, a disorder characterised by random bursts of activity in brain that can easily be detected on a screen
  • extremely high temporal resolution - unlike fMRI, can detect accurately at resolution of a millisecond or less
  • shows real world usefulness of technique
• EEG eval - weaknesses :(

  • generalised nature of info received - many thousands of neurons
  • EEG signal isnt useful for pinpointing exact source of neural activity - doesnt allow researchers to distinguish between activities going on in different but adjacent locations
• ERP eval - strengths :)

  • much more specified - unlike EEPs, more specificity to measurement of neural processes
  • excellent temporal resolution - as theyre derived from EEGs
  • meaning theyre frequently used to measure cognitive functions and deficits eg. allocation of attentional resources and maintenance of working memory
• ERP eval - weaknesses :(

  • lack of standardisation in ERP methodology between diff research studies - makes it difficult to confirm findings
  • background noise and extraneous material must be completely eliminated - in order to establish pure date, not always easy to achieve