Ways of studying the brain

• Outline post-mortems as a way of studying the brain.


  Post-mortem examinations are carried out on individuals who displayed abnormal behaviour during their lifetime.

  Upon their death, their brain is physically examined and compared to a neurotypical brain to assess whether there is any structural damage.

  Any observed damage to their brain is assumed to be responsible for the abnormal behaviour they displayed in their lifetime.
• Identify the three scanning

  techniques.

  fMRI, EEGs and ERPs.
• Outline fMRI as a scanning technique.


  This is because it involves using a large magnetic field and radio frequency waves to produce a 3D image of the brain and which areas are most active.

  Its measurement of brain activity is indirect, it measures blood flow.

  This is because active neurons require energy in the form of oxygen and so the active areas receive more blood.

  If a brain area consistently receives more blood flow during a task, it is indicated as highly active on the 3D image of the brain and is assumed to be responsible for that task
• Outline EEGs as a scanning technique.


  EEGs are primarily used to study whether brain wave activity is rhythmic or not.

  It is therefore used to measure general brain activity such as that associated with sleep.

  EEGs involve placing electrodes on the scalp which directly measure neural activity in the cortex (outer surface) of the brain.

  The electrical activity caused by the firing of neurons is graphed over time to show the level of brain activity.
• Outline ERPs as a scanning technique.


  ERPs are used to time how quickly cortical brain regions respond to events e.g. a sensory stimulus.

  The timing of these responses can then be used to inform researchers of how quickly the brain communicates.

  ERPs involve placing electrodes on the scalp which directly measure neural activity in response to an event.

  This means that a stimulus is presented approximately 100 times and then an averaging technique is used to generate a graph of the consistent brain activity in response to that stimulus.
• Evaluate post- mortems: informed us about localisation and hemispheric lateralisation of the brain.


  E.g. Broca’s post mortem research found that a patient with speech production difficulties had damage to Broca’s area while Wernicke’s post mortem research found that a patient with language comprehension difficulties had damage to Wernicke’s area. This is a strength as such research showed how language functions are localised to specific areas of the brain and also tend to be lateralised to the left hemisphere.
• Evaluate post- mortems: difficult to establish cause and effect in post mortems. 


  This is because confounding variables such as the natural decay of the brain after death could affect the analysis. This is a limitation because it may ean the structural damage found in a post-mortem examinations could be unrelated to the abnormal behaviour the patient displayed (it may just be that their brain had started to decay after death).
• Evaluate post- mortems: suffer from small sample sizes. 


  This is because they require informed consent which can be difficult to gain from patients with disorders that make them of interest. If consent is gained from family after death, it must be fast to reduce the risk of brain decay taking place before the physical examination. This is a limitation because small sample sizes limit the generalisability of the conclusions drawn from post mortems.
• Evaluate fMRI: high spatial resolution. 


  This is because it produces a 3D image of the brain that can identify brain activity to within 1mm of its location. This is a strength because the ability to accurately locate brain activity has informed us about localisation of function in the brain (e.g. how

  increased activity in Broca’s area during a speech production task has helped us to understand the role of Broca’s area in speech production).
• Evaluate fMRI: low temporal resolution.


  This is because it is an indirect measure of brain activity due to its reliance of measuring blood flow rather than the actual firing of neurons. This is a limitation because there is a delay before an active brain area receives increased blood flow and so it can be difficult to assess whether it is related to the task the participant is currently performing.
• Evaluate fMRI: practical limitations.


  E.g. fMRI requires patients to stay still for a clear image and, due to its use of advanced technological equipment, is expensive to run. This is a limitation because the need for the patient to stay still limits its use when studying young children or people with movement disorders. Also, its costly nature means that sample sizes are often small, limiting the generalisability of any conclusions drawn.
• Evaluate EEGs/ERPs: high temporal resolution. 


  This is because they are direct measures of brain activity and so can detect it within milliseconds. This is a strength because it enables researchers to accurately identify the onset and timing of brain activity.
• Evaluate EEGs/ERPs: cheap to use.


  This is because they do not require as much technological equipment as an fMRI (e.g. just use electrodes as opposed to expensive machines creating large magnetic fields). This is a strength because it means EEGs/ERPs can be used on larger samples without research costs becoming an issue and, as a result, the findings are more likely to be generalisable.
• Evaluate EEGs/ERPs: low spatial resolution. 


  This is because the electrodes can only detect general areas of cortical brain activity (i.e. activity in the outer surface of the brain). This is a limitation because it means it is unable to detect brain activity in the deeper areas of the brain

  or accurately locate the specific area of activity.