ways of studying the brain

• functional magnetic resonance imaging (fMRI) -

  • 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 area is more active it consumes more oxygen and to meet this increased demand blood flow is directed to the active area
  • fMRI produces 3D images showing which parts of the brain are involved in a particular mental process
  • important implications for our understanding of localisation of function
• electroencephalogram (EEG) -

  • measures electrical activity within the brain via electrodes that are fixed to an individuals scalp
  • the scan recording represents the brainwave patterns that are generated from the action of thousands of neurons providing an overall amount of brain activity
  • often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy, tumours or some sleep disorders
• EEG clinical applications -

  • EEG has many scientific and clinical applications - in its raw form its a crude and overly general measure of brain activity
  • however within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscience - researchers have developed a way of teasing out and isolating these responses
• event related potentials -

  • using a statistical averaging technique - all extraneous brain activity from original EEG recording is filtered out - leaving only those responses that relate to the presentation of a specific stimulus or performance of a specific task
  • what remains are event related potentials (ERPs) - types of brainwave that are triggered by particular events
  • research has revealed many different forms of ERP and how, for example, these are linked to cognitive processes such as attention and perception
• post mortem examinations -

  • technique involving the analysis of a persons brain following their death
  • psychological research - likely to be individuals who have a rare disorder and have experienced unusual deficits in cognitive processes or behaviour during their lifetime
  • areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person experienced
  • may involve comparison with a neurotypical brain to ascertain the extent of the difference
• evaluation of fMRI: strength -

  • P: unlike other scanning techniques such as PET it doesn't relay on use of radiation
  • E: if administered correctly its virtually risk-free, non-invasive and straightforward
  • E: also produced images that have a very high spatial resolution, depicting detail by the millimetre and providing a clear picture of how brain activity is localised
  • P: means fMRI can safely provide a clear picture of brain activity
• evaluation of fMRI: limitation -

  • P: expensive compared to other neuroimaging techniques
  • E: poor temporal resolution because of 5 sec time lag behind image on screen and the initial firing of neuronal activity
  • P: means it may not truly represent moment to moment brain activity
• evaluation of EEG: strengths -

  • P: useful in studying the stages of sleep and in diagnosis of conditions such as epilepsy - disorder characterised by random bursts of activity in the brain that can easily be detected on screen
  • E: unlike fMRI, EEG technology has extremely high temporal resolution
  • E: today's EEG technology can accurately detect brain activity at a resolution of a single millisecond
  • L: shows real-world usefulness of technique
• evaluation of EEG: limitations -

  • P: main drawback lies in generalised nature of the information received (many thousands of neurons)
  • E: EEG signal is also not useful for pinpointing the exact source of neural activity
  • L: doesn't allow researchers to distinguish between activities originating in different but adjacent locations
• evaluation of ERPs: strength -

  • P: limitations of EEG are partly addresses through the use of ERPs
  • E: these bring much more speciality to the measurement of neural processes than could be achieved using raw EEG data
  • E: as ERPs are derived from EEG measurements they have excellent temporal resolution
  • L: means ERPs are frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and the maintenance of working memory
• evaluation of ERPs: limitation -

  • P: critics have pointed to a lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings
  • E: further issue is in order to establish pure data in ERP studies background 'noise' and extraneous material must be completely eliminated
  • L: this is a problem because it may not always be easy to achieve
• evaluation of post mortem examinations: strength -

  • P: vital in providing a foundation for early understanding of key processes in the brain
  • E: Broca and Wernicke relied on post mortem studies in establishing links between language, brain and behaviour decades before neuroimaging
  • E: also used to study HM's brain to identify the areas of damage which could be associated with his memory deficits
  • L: means post-mortems continue to provide useful info
• evaluation of post mortem evaluations: limitations -

  • P: causation is an issue within these studies
  • E: observed damage to the brain may not be linked to the deficits under review but to some other related trauma or decay
  • E: further problem is that post-mortem studies raise ethical issues of consent from the individual before death - HM lost ability to form memories and unable to provide such consent - conducted post mortem research anyway
  • L: challenges usefulness of post-mortem studies in psychological research