Ways of studying the brain

• Functional magnetic resonance imaging fMRI

  = Method used to measure brain activity while a person is performing a task.

  • Works by detecting the changes in both blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain.
  • When a brain is more active it consumes more oxygen, blood flow is directed to the active area.
  • fMRI produces 3D images showing which parts of the brain are involved in particular functions.
• fMRI strengths:

  • Doesn't rely on the use of radiation.
  • Virtually risk free, non-invasive and straightforward to use.
  • Produces images that have high spatial resolution, providing a clear picture of how brain activity is localised
  • fMRI can safely provide clear picture of brain activity
• fMRI limitations:

  • Expensive
  • Poor temporal resolution because of 5 second time lag behind image on the screen and initial firing of neuronal activity.
  • So cant truly represent moment to moment brain activity.
• Electroencephalogram EEG:

  = Measures electrical activity within the brain via electrodes that are fixed to an individuals scalp.

  • Recordings represents the brainwave patterns that are generated from action of thousands of neurones, providing overall account of brain activity. 
  • Used as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities- epilepsy, tumours.
• EEG strengths:

  • Useful in studying stages of sleep, diagnosis of conditions like epilepsy, a disorder characterised by random bursts of activity in the brain that can easily be detected on screen.
  • High temporal resolution
  • Can accurately detect brain activity at a resolution of a single millisecond
• EEG limitations:

  • EEG signal is not useful for pinpointing the exact source of neural activity.
  • Therefore it does not allow researchers to distinguish between activities originating in different but adjacent locations.
• Event-related potential

  = The electrophysiological response of the brain to a specific sensory, cognitive or motor event can be isolated through analysis of EEG data.
• ERP strengths:

  • As ERP are derived from EEG measurements, they have excellent temporal resolution.
  • So ERP frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and the maintenance of working memory.
• ERP limitations:

  • Lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings.
  • In order to establish pure data in ERP studies, background 'noise' and extraneous material must be completely eliminated, which may not be easy to achieve.
• Post-mortem examinations

  = Brain is analysed after death to determine whether certain observed behaviours during the person's lifetime can be linked to structural abnormalities in the brain.
• post-mortem examinations strengths:

  • Vital in providing a foundation for early understanding of key processes in the brain.
  • Broca and Wernicke both relied on post-mortem studies in establishing links between language, brain and behaviour before neuroimaging became a possibility.
  • Also used to study HM's brain to identify areas of damage associated with memory deficits.
• post-mortem examinations limitations:

  • Observed damage to the brain may not be linked to deficits under review but to some other unrelated trauma or decay.
  • Raise ethical issue of consent from individual before death.
  • Participants may not be able to provide informed consent.