ways of studying the brain

• studying the brain

  • 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 which parts of the brain do what
• functional magnetic resonance imaging (fMRI)

  • Detects changes in both blood oxygenation and flow that occur due to neural activity in specific brain areas
  • When a brain area is more active it consumers more oxygen and blood flow is directed to the active areas (haemodynamic response)
  • FMRI produces a 3D image showing which parts of the brain are active and therefore must be involved in particular mental processes
  • ‘highlights active areas in the brain’
• fMRI evaluation:

  • Strength = risk-free and high spatial resolution:
  • Unlike other scanning techniques (eg PET) fMRI doesn’t rely on the use of radiation and is safe
  • It also produces images with a high spatial resolution (showing email by the millimetre)
  • Means fMRI can safely provide a clear picture of how brain activity is localised
  • Limitation = expensive and poor temporal resolution:
  • FMRI is expensive compared to other techniques
  • Has poor temporal resolution because of 5-second lag between initial neural activity and image
  • Means fMRI may mot truly represent moment-to-moment brain activity
• Electroencephalogram (EEG)

  • Measures electrical activity within the brain via electrodes using a skull cap
  • The scan recording represents the brainwave patterns generated from thousands of neurons (shows overall brain activity)
  • EEG is often used as a diagnostic tool
  • Eg = unusual arrhythmic patterns of brain activity may indicated abnormalities (such as epilepsy, tumours, sleep disorders)
  • ‘Shows overall electrical activity‘
• EEG evaluation:

  • Strength = practical uses and high temporal resolution:
  • EEG has contributed to our understanding of the stages of sleep
  • Has high temporal resolution (brain activity in one second)
  • Shows the real world usefulness of the technique
  • Limitation = information is generalised and source not pinpointed
  • EEG produces a general use signal from thousands of neurons
  • It is difficult to know the exact source of neural activity (low spatial resolution)
  • => EEG can’t distinguish the activity of different but adjacent neurons
• event-related potentials (ERPs)

  • 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 (for example)
  • 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 (eg perception and attention)
  • ‘Brainwaves related to particular events’
• ERP evaluation:

  • Strength = specificity and good temporal resolution:
  • Measures of neural processes more specific with ERPs that EEGs
  • ERPs have excellent temporal resolution (better than fMRI)
  • Means that ERPs are frequently used in cognitive research
  • Limitation = lack standardisation and background ‘noise’:
  • Lack of standardisation makes it difficult to confirm findings in studies involving ERPs
  • Background ‘noise’ and extraneous material must be completely eliminated
  • These issues are a problem becuase they may not always be easy to achieve
• post-mortem examinations

  • A techniques involving the analysis of a person‘s brain following their death
  • Areas of the brain are examined to establish the likely cause of a deficit or disorder that the person experienced in life
  • this may involve comparison with a neurotypical brain in order to assess the extent of the difference
• post-mortem examinations evaluation:

  • Strength = localisation and medical research:
  • Broca and Wernicke both relied on post-mortem studies
  • Used to link HM’s memory deficits to damage in his brain
  • Means they continue to provide useful information
  • Limitation = causation and ethics:
  • Observed damage in the brain may not be linked to the deficits under review (eg may be due to decay etc)
  • Post-mortem studies raise ethical issues of consent after death (eg HM)
  • This challenged their usefulness in psychological research