Studying the Brain

• fMRI


  • detecting the changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain
  • when a rain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area
  • produces a 3D image showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of functions
• Evaluation of fMRIs

  • doesn't rely on the use of radiation
  • it produces images that have very high spatial resolution, depicting detail by the mm, and providing a clear picture of how brain activity is localised
  • it is expensive and can only capture a clear image if the person stays perfectly still
  • it has poor temporal resolution because there is around a 5 second time lag behind the image on screen and the initial firing of neuronal activity
  • can only measure blood flow in the brain and can't home in on the activity of individual neurons and so it can be difficult to tell exactly what kind of brain activity is being represented on screen
• EEG

  • measure electrical activity within the brain via electrodes that are fixed to an individual's scalp using a skull cap
  • the scan recording represents the brainwave patterns that are generated from the millions of neurons, providing an overall account 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 sleeping disorders
• Evaluation of EEGS

  • it is a crude and overly general measure of brain activity
  • in the data all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists
  • invaluable in the diagnosis of conditions
  • has contributed to much of our understanding of the stages involved in sleep
  • high temporal resolution of a single millisecond
  • it is not useful for pinpointing the exact source of neural activity and it doesn't allow researcher to distinguish between activities originating in different but adjacent locations
• ERPs

  • using statistical average technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to remains are event-related potentials
  • types of brainwaves that are triggered by particular events
  • research has revealed many forms of ERP and how these are linked to cognitive processes such as attention and perception
• Evaluation or ERPs

  • excellent temporal resolution, especially when compared to neuroimaging techniques such as fMRI and this has led to their widespread use in the measurement of cognitive functions and deficits
  • there is a lack of standardisation in ERP methodology between different research studies which make it difficult to confirm findings
  • in order to establish pure data, background noise and extraneous material must be completely eliminated, which isn't easy
• Post-mortem exams

  • the analysis of a person's brain after they've dies
  • individuals brains who are subject to post-mortem are likely those who have a rare disorder and have experienced unusual deficits in mental 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 experiences
  • this may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference
• Evaluation of post-mortem

  • vital in providing a foundation for early understanding of key processes in the brain
  • they improve medical knowledge and help generate hypotheses for further study
  • causation is an issue as observed damage to the brain may not be linked to the deficits under review but some other unrelated trauma or decay
  • raise an ethical issue of consent from individuals before death as some may not be able to provide informed consent