Ways of studying the brain

• What are post-mortem examinations?

  • Analysis of a person's brain following their death - mainly used before the relevant technology existed
  • Likely to be those have a rare disorder or experienced unusual deficits in cognitive/behavioural processes during their lifetime
  • Can help us learn about mental disorders by comparing their brains to neurotypical brains
• What is one strength of post-mortem examinations?

  • Historical power: PMs were vital in providing a foundation for early understanding of key processes in the brain
  • Broca and Wernicke both relied on PMs to establish links between language, behaviour, and the brain before neuro-imaging existed - were also used to study HM's brain to associate damage with his memory deficits
  • Means PMs have provided useful information
• What is one limitation of post-mortem examinations?

  • Causation: observed damage to the brain may not be linked to what they were reviewing but other unrelated trauma or decay such as disease or cause of death
  • Also raises ethical issues and cultural relativism as participants are unable to provide informed consent, such as HM who couldn't form memories
  • PMs are not permitted in certain cultures and religions such as Islam, making them limited in use
• What are fMRIs? What are activation maps?

  • Brain scans that work by detecting changes in blood oxygenation that occurs as a result of neural activity in specific brain areas
  • Active brain areas consume more oxygen meaning blood flow is directed to these areas
  • Activation maps: 3D images showing which parts of the brain are more oxygenated and therefore more active
• What is spatial and temporal resolution?

  • Spatial resolution - detailed brain images showing the space/areas of increased activity
  • Temporal resolution - brain image/reading is done at the same time as the task causing activity
• What is one strength of fMRIs?

  • Risk-free: doesn't rely on the use of radiation like PETs and is non-invasive and straightforward to use when administered correctly
  • High spatial resolution: produces images exact to 1mm, providing a clear picture of localised activity
  • Means fMRIs can safely provide a clear picture of brain activity
• What is one limitation of fMRIs?

  • Poor temporal resolution: there is a 5-second lag between the firing of neurons and the image captures, and it can only measure blood flow rather than the type of activity
  • Difficult: person under review has to stay completely still for the image to be captured, which can be problematic for children, claustrophobes or people who experience tics
• What are EEGs?

  • Brain images that measure electrical activity within the brain via electrodes fixed on the scalp through a skull cap
  • Scan recording represents the brainwave patterns that are generated from the action of thousands of neurons, providing an overall account of brain activity
  • Often used by clinicians to look for arrhythmic patterns of activity (no particular rhythm) which can be used to detect types of brain disorders like epilepsy or Alzheimer's
• What is one strength of EEGs?

  • High temporal resolution: can accurately detect brain activity at 1 millisecond
  • Value: important in diagnosis of epilepsy characterised by random bursts of activity which can be easily detected by EEGs
• What is one limitation of EEGs?

  • Generalised information: signals aren't useful for pinpointing the exact source of neural activity, meaning it doesn't allow researchers to distinguish between activities originating in different but adjacent locations
  • Poor spatial resolution further limits this, as it doesn't allow for activity to be linked to locations in the brain
• What are ERPs?

  • Event-related potentials isolate specific neural responses of interest from an original EEG report
  • Use statistical averaging techniques (conducting over 100 trials to average results together and filtering out extraneous brain activity), meaning what remains is the event-related potential that consists of brainwaves triggered by particular events
• What is one strength of ERPs?

  • Experimentally robust: brings much more specificity to the measurement of neural processes than could ever be achieved using raw EEG data
  • Excellent temporal resolution, meaning ERPs are frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and the maintenance of working memroy
• What is one limitation of ERPs?

  • Critics point to a lack of standardisation in ERPs methodology between different research studies, making it difficult to confirm findings
  • To establish pure data, background 'noise' and extraneous material must be completely eliminated, yet this is not always easy to achieve