Ways of Studying the Brain

  • techniques for investigating brain are often used for medical purposes in diagnosis of illness. purpose of scanning in psychological research is often to investigate localisation - to determine which parts of the brain do what.
  • evaluation of FMRI
  • electroencephalogram (EEG)

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  • functional magnetic resonance imaging (FMRI)
  • works by detecting changes in both blood oxygenation and flow that occur as result of neural activity in specific parts of brain.
  • brain area more active = consumes more oxygen & to meet increased demand, blood flow is directed to active area
    (known as the haemodynamic response)
  • FMRI produces 3-dimensional images (activation maps) showing which parts of brain are involved in specific mental processes - has important implications for our understanding of localisation of function.
  • STRENGTHS
  • doesn't rely on use of radiation like PET scans.
  • is risk-free, non-invasive, and straightforward to use. when administered correctly
  • produces images that have very high spatial resolution depicting detail by mm and providing clear picture of how brain activity is localised - means FMRI can safely provide a clear picture of brain activity.
  • LIMITATIONS
  • Expensive compared to other neuroimaging techniques
  • has poor temporal (time) resolution because of 5 sec time lag behind image on screen & initial firing of neural activity - means FMRI may not truly represent moment-to-moment brain activity.
  • measure electrical activity within brain via electrodes which are fixed to an individual's scalp using a skull cap.
  • scan recording represent brainwave patterns which are generated from action of thousands of neurons, providing overall account of brain activity.
  • often used by clinicians as diagnostic tool as unusual arrhythmic patterns of activity. (i.e. no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours or some sleep disorders.
  • Evaluation of EEG
  • STRENGTHS
  • has been useful in studying stages of sleep & in diagnosis of conditions such as epilepsy, a disorder characterised by random bursts of activity in brain which can easily be detected on the screen.
  • Has extremely high temporal resolution - today's EEG tech can accurately detect brain activity at a resolution of a single millisecond - shows the real-world usefulness of the technique
  • WEAKNESSES
  • main drawback of EEG lies in generalised nature of info received (that of many thousands of neurones)
  • EEG signal isn't useful in pinpointing exact source of neural activity - therefore doesn't allow research to distinguish between activities originating in different adjacent locations
  • Event-related potential (ERP)
  • ERPs are a way of teasing out and isolating specific neural responses associated with sensory, cognitive, and motor events.​
  • ERPs work by using statistical averaging techniques, that filters out extraneous brain activity from the original EEG recording, leaving only the responses that relate to say, the presentation of a specific stimulus or performance of a specific task.​
  • Event-related potentials = types of brainwave that are triggered by particular events.​
  • Research has shown different forms of ERPs, linked to cognitive processes such as attention and perception.​
  • Evaluation of ERP
  • STRENGTHS
  • WEAKNESSES
  • ERPs bring much more specificity to the measurement of neural processes than could be achieved using raw EEG data.​
  • As ERPs are derived from EEG measurements, they have excellent temporal resolution - led to their widespread use in the measurement of cognitive functions and deficits.​
  • Researchers have been able to identify many different types of ERP & describe the precise role of these in cognitive functioning including parts of working memory​
  • A lack of standardisation in ERP methodology between different research studies make it difficult to confirm findings.​
  • In order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which is not always easy to do.​

EXTRA SPACE

  • post-mortem examinations (PME)
  • This is a technique that involves the analysis of a person’s brain following their death.​
  • Likely to be carried out on those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour:​
  • Areas of damage within the brain are examined after death as a means of establishing the likely cause​
  • May also involve comparison with a neurotypical (healthy) brain in order to see the extent of the difference​
  • Evaluation of PME
  • STRENGTHS

-WEAKNESSES

  • Post-mortem (PM) evidence was vital in providing a foundation for early understanding of key processes in the brain.​
  • Both Broca & Wernicke relied on PM studies in establishing links between language, brain, and behaviour decades before neuroimaging began
  • Still help to improve medical knowledge and help generate hypotheses for further study. (case of HM – memory)
  • Causation is an issue within these investigations:


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

  • PM studies raise ethical issues of consent from the patient before death particularly informed consent​


  • e.g. case of HM who lost his ability to form memories and was not able to provide such consent​