Studying the brain

• FMRI


  Functional magnetic resonance imaging works by detecting changes in blood flow and oxygenation due to neural activity. More active areas require more oxygen and greater blood flow. FMRI produces 3D images and has important implications for our understanding of the localisation of function.
• EEG


  Electroencephalogram (EEG) measures electrical activity using electrodes attached to the scalp with a scull cap. The scan records the brain wave patterns generated from the action of thousands of neurons, providing an overall account of brain activity. EEG is often used by clinicians as a diagnostic tool as arrhythmic patterns may indicate neurological abnormalities such as epilepsy, and tumours of sleep disorders.
• Event-related potentials


  What is left when all extraneous brain activity from an EEG recording is filtered out. This is done using a statistical technique, leaving only those responses that relate to the presence of a specific stimulus. ERPs are types of brain waves that are triggered by specific events. Research has revealed different types of ERPs and how they are linked to cognitive processes.
• Post-mortem examinations


  Analysing a person's brain following their death. Usually done on people who have had a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime. Areas of damage are examined to establish the likely cause. It may also involve comparing to a neurotypical brain to establish the extent of the difference.
• Strengths of FMRIs


  doesn't rely on radiation, and if administered correctly is virtually risk-free, non-invasive and straightforward to use

  Produces images with high spatial resolution, depicting detail by the millimetre, providing a clear picture of how brain activity is localised.
• Limitations of FMRIs


  FMRIs are expensive in comparison to other neuroimaging techniques

  They have poor temporal resolution, with a 5-second time lag behind the image on the screen and initial firing on neurological activity. This means fMRIs may not truly represent moment-to-moment brain activity.
• Strengths of EEGs


  EEGs have been useful in studying the stages of sleep and diagnosis of conditions such as epilepsy, which is characterised by random bursts of brain activity.

  EEGs have high temporal resolution, detecting brain activity at a single millisecond.
• Limitations of EEGs


  EEGs are not useful for pinpointing the exact source of neural activity. Therefore doesn't allow researchers to distinguish between activities originating in different but adjacent locations.
• Strengths of ERPs

  ERPs bring much more specificity to measurement of neural processes than the use of raw EEG data.

  ERPs have high temporal resolution so are frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and maintenance of working memory.
• Limitations of ERPs


  There is a lack of standardisation of ERP methodology, making it difficult to confirm findings.

  In order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated. This may not be easily done.
• Strengths of Post-Mortem examinations

  Post-mortem evidence was essential in the early understanding of the brain. Broca and Wernicke relied on them to establish links between language, brain and behaviour decades before neuro-imaging was possible.

  Post-mortem exams were also used to study HM's brain to identify areas of damage, that could then be associated with his memory deficits. Meaning they still provide useful information.
• Limitations of Post-Mortem examinations


  Observed damage may not be linked to the deficits under review but rather some unrelated trauma or decay.

  There are ethical issues of consent. The participant may not be able to provide informed consent, for example, HM lost his ability to form memories and was unable to give informed consent, research was still performed.