Ways of studying the brain

• fMRI (Functional Magnetic Resonance Imaging)


  Detects changes in the blood oxygenation and flow as a result of neural activity in different parts of the brainIf an area is activated, more oxygen is directed to the area (haemodynamic response)Produces 3D images showing active areas in the brain
• fMRI Strengths

  • Doesn't rely on radiation
  • If administered correctly, virtually risk-free, non-invasive and straightforward
  • Produces images with high spatial resolution, depicting detail by the millimeter and providing a clear picture of how brain activity is localized
• fMRI Weaknesses

  • Expensive
  • Only establishes a clear picture if person lays completely still
  • Poor temporal resolution - 5 second lag time
  • Only measures blood flow, not individual activity, therefore, it is difficult to tell what brain activity is being represented
• EEG (Electroencephalogram)


  • Measures electrical activity within the brain via electrodes that are fixed on the scalp via a skull cap.
  • Shows brainwave patterns generated from millions of neurons providing overall account of activity.
  • Often used by clinicians as a diagnostic tool as usual patterns may indicate abnormality e.g. epilepsy.

  
• EEG Strengths

  • Invaluable in the diagnoses of conditions such as epilepsy - disorder characterized by random bursts of activity in the brain that is easily detected on screen
  • Contributed to our understanding of stages of sleep
  • Unlike fMRI, has a high temporal resolution. Today, technology can accurately detect at a millisecond
• EEG Weaknesses

  • Generalised information produced (thousands of neurons)
  • Signal is not useful for pinpointing exact source of neural activity
  • Does not allow researchers to distinguish between activities originating in different but adjacent locations
• ERPs (Event-Related Potentials)

  Using statistical averaging technique all extraneous brain activity from original EEG is filtered leaving only responses that relate to a particular stimulus.What remains is event-related potentials = types of brainwaves that are triggered by particular events. Research has revealed different forms of these.
• ERP Strengths

  • High temporal resolution
  • Widespread use in measurement of cognitive functions and deficits
  • Researchers have identified more than one of these with multiple functions e.g. p300 component is thought to be involved in the allocation of attentional resources and maintenance of working memory.
• ERP Weaknesses

  • Lack of standardization in methodology between different research studies = makes it hard to confirm findings.
  • In order to establish pure data in studies, background noise and extraneous variables/materials must be eliminated - this is not always easy
• Post-Mortem Examinations

  Analysis of a person's brain after death.Those subject to this are likely to be those who had a rare disorder or experienced unusual deficits during their lifetime. 
• Post-Mortem Examinations Strengths

  • Vital in providing a foundation for an early understanding of key processes in the brain.
  • Broca and Wernicke both relied on this for establishing links between the brain and language
  • Improves medical knowledge and generates hypotheses for further studies
• Post-Mortem Examinations Weaknesses

  • Causation - observed damage may not link to deficits under review but maybe will link to another illness or trauma
  • Ethical concerns: consent - If patients don't give consent, it is unethical e.g. the case of HM
• Temporal resolution

  refers to the accuracy of the scanner in relation to time: or how quickly the scanner can detect changes in brain activity.