Ways of investigating the brain (Scanning)

• Weakness of Post-mortem examinations

  1. Causation: observed damage to the brain may not be linked to the deficits under review but someother related trauma or decay

  2. Raises ethical issues of consent from individuals before death.

  
  

  EXAMPLE: H.M. lost is ability to form memories therefor loosing the ability to give informed consent yet research was still conducted on him
• Strengths of Post-mortem examinations

  1. Vital in providing a foundation for early understanding of key processes in the brain

  2. relied on PME in establishing links between, language brain and behaviour before neuroimaging

  3. improved medical knowledge and help generate hypotheses for further studies
• Post-Morem examinations

  • the analysis of a persons brain after death
  • likely to be those with rare disorders/ those with unusual defects with mental process
  • may involve comparison with neurotypical brain

  
• Weaknesses of ERPs

  1. lack of standardisation in ERP methodolgy between different research studies --> making it difficult to confirm findings.

  2. Background noise + extraneous material must be completely eliminated
• Strengths of ERPs

  1. more specific than using EEG

  2. good temporal resolution, led to widespread use in the measurements of cognitive functions and defects

  3. have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning
• ERPs

  Event-related Potentials

  • Contains all the neural responses associated within a specific sensory, cognitive and motor events that may be interest to cognitive neuroscientists
  • can show brain activity related to the specific stimulus chosen
  • the type of brain waves that are triggered buy particular events

  
• Weaknesses of EEG's

  1. The nature of which the information is received - not useful in pin pointing the exact source of the neural activity

  2. Doesn't allow researchers to distinguish activities originating in different but adjacent locations
• Strengths of EEG's


  1. Provides valuable in the diagnosis of conditions (epilepsy)

  2. Contributed to our understanding of the stages of sleep

  3. Has high temporal resolution

  4. Can accurately detect brain activity at a resolution of a single millisecond
• EEG

  Electroencephalogram

  • Measures electrical activity within the brain via electrodes that are fixed to an individual scalp using a skull cap
  • shows the brainwave patterns that are generated from the action of neurons - providing an account of brain activity
  • used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities (epilepsy, tumours and disorders of sleep)

  
• Weaknesses of fMRI

  1. Expensive compared to other neuroimaging techniques and can only capture a clear image if person is completely still
  2. Poor temporal resolution - 5 second time lag behind the image on screen and the initial firing of neuronal activity
  3. Can only measure blood flow in the brain, cannot home in on the activity of individual neurons (can be difficult to tell exactly what kind of brain activity is being represented)
• Strengths of fMRI

  1. Doesn't rely on the use of radiation. If administered correctly it can be risk-free, non-invasive and straight forward to use
  2. Produces images that have very high spatial resolution, depicting detail by the and providing clear pictures of how brain activity is localised
• fMRI

  Functional Magnetic resonance imaging

  • measures blood oxygenation that occurs as a result of neural activity in specific parts of the brain
  • produces 3d images showing which part of the brain is involved in which mental process
  • has a spatial recognition of approx. 1-2mm

  
• What are the 4 ways of investigating the brain?

  1. functional magnetic resonance imaging (fMRI)

  2. electroencephalogram (EEG)

  3. event-related potentials (ERPs)

  4. post-mortem examinations