Ways of Investigating the Brain

• Spatial Resolution


  level of accuracy in identifying the exact location of the brain structure or brain activity in space (where activity happened)
• Temporal Resolution


  level of accuracy in identifying the exact location of a brain activity in time (when the activity happened)
• fMRI (functional magnetic resonance imaging)

  - detects the changes in oxygenation of blood and flow that occurs as a result of neural activity in specific parts of the brain.

  - provides 3D image showing parts of the brain involved in a particular mental process -> important implications for our understanding of localisation of function.

  - haemodynamic response -> brain area requires more oxygen, more blood goes towards that area.
• Strength - fMRI


  - doesn't rely on use of radiation.

  - if administered correctly it's virtually risk-free, non-invasive and straight forward to use.

  - images have high SPATIAL resolution -> clear picture of localisation.
• Weakness - fMRI


  - expensive

  - poor TEMPORAL resolution as there's around a 5s time lag behind the image on screen and initial firing of neuronal activity -> may not truly represent moment to moment brain activity.

  - only measures blood flow and not neural activity.
• EEG (electroencephalogram)


  - measure electrical activity within the brain via electrodes that are fixed to someone's scalp using a skull cap.

  - records the brainwave patterns that are generated from the action of thousands of neurones, providing on overall account of brain activity.

  - used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity
• Strength - EEG


  - useful to study sleep and diagnosing conditions like epilepsy -> random bursts of activity.

  - extremely high TEMPORAL resolution -> accurately detect brain activity at a resolution of a single millisecond.
• Weakness - EEG


  - not useful at pinpointing the exact source of neural activity -> doesn't allow researchers to distinguish between activities originating in different but adjacent locations.

  - only reads surface level signals may be deeper.
• ERP (event related potential)

  - types of brainwaves that are triggered by particular events.

  - linked to cognitive processes such as attention and perception.

  - 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.
• Strength - ERP


  - more specificity to the measurement of neural processes that could ever be achieved using raw EEG data.

  - excellent TEMPORAL resolution

  - frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and the maintenance of working memory.
• Weakness - ERP


  - lack of standardisation in ERP methodology between different research studies -> difficult to confirm findings.

  - background 'noise' and extraneous material must be completely eliminated -> not easy to achieve.
• Post-mortems


  - analysis of a person's brain following their death.

  - likely to have a rare disorder and have experienced unusual deficits in cognitive processes or behaviour during their lifetime.

  - areas of brain damage are examined after death -> establish the likely cause of the affliction the person experienced.

  - may involve comparison with a neurotypical brain.
• Strength - post-mortems


  - provides a foundation for early understanding of key processes in the brain.

  - Broca and Wernicke both relied on post-mortem studies to establish links between language, brain and behaviour decades before neuroimaging became possible.
• Weakness - post-mortems


  - causation -> observed brain damage may not be linked to the deficits under review but some other unrelated trauma or decay.

  - raise ethical issues of consent from the individual before death -> ppts may not be able to provide informed consent e.g. HM who lost his ability to form memories and wasn't able to provide such consent - post-mortem research has been conducted on his brain.