Studying the Brain

• what are fMRI?

  • measures blood flow when a person performs a task and creates a dynamic (moving) 3D map of the brain, highlighting which areas are involved in different neural activities.
• are fMRI invasive or non-invasive?

  • non-invasive: unlike other scanning techniques fMRI does not use radiation or involve inserting instruments directly into the brain, and is therefore virtually risk-free
  • consequently, this should allow more patients/participants to undertake fMRI scans which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of localisation of function
• spatial resolution of an fMRI

  • good spatial resolution as they can discriminate between different brain regions with greater accuracy
  • have a spatial resolution of approximately 1-2 mm which is significantly greater than the other techniques
  • psychologists can determine the activity of different brain regions with greater accuracy when using fMRI in comparison to EEG/ERP
• temporal resolution of an fMRI

  • poor temporal resolution as fMRI scans have a temporal resolution of 1-4 seconds which is worse than other techniques (e.g. EEG/ERP which have a temporal resolution of 1-10 milliseconds).
  • psychologists are unable to predict with a high degree of accuracy the onset of brain activity.
• causation of an fMRI

  • fMRI scans do not provide a direct measure of neural activity. fMRI scans simply measure changes in blood flow and therefore it is impossible to infer causation (at a neural level).
  • While any change in blood flow may indicate activity within a certain brain area, psychologists are unable to conclude whether this brain region is associated with a particular function.
  • In addition fMRI are limited in showing the communication that takes place among the different areas of the brain, which might be critical to neural functioning.
• what are EEGs?

  • measures electrical activity through electrodes attached to the scalp. Small electrical charges are detected by the electrodes that are graphed over a period of time, indicating the level of activity in the brain.
• what are ERPs?

  • uses similar equipment to EEG.
  • However, the key difference is that a stimulus is presented to a participant and the researcher looks for activity related to that stimulus.
• are EEGs and ERPs invasive?

  • An advantage of EEG and ERP is that both techniques are non-invasive.
  • Unlike other scanning technique EEG and ERP do not use radiation or involve inserting instruments directly into the brain and are therefore virtually risk-free.
  • Furthermore, EEG and ERP are much cheaper techniques in comparison with fMRI scanning and are therefore more readily available.
  • Consequently, this should allow more patients/participants to undertake EEG/ERPs, which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding
• spatial resolution of EEG/ERP

  • poor spatial resolution
  • EEGs/ERPs only detect the activity in superficial regions of the brain.
  • Consequently, EEGs and ERPs are unable to provide information on what is happening in the deeper regions of the brain (such as the hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm.
• temporal resolution of EEG/ERP

  • good temporal resolution: it takes readings every millisecond, meaning it can record the brain’s activity in real time as opposed to looking at a passive brain.
  • This leads to an accurate measurement of electrical activity when undertaking a specific task.
  • However, it could be argued that EEG/ERP is uncomfortable for the participant, as electrodes are attached to the scalp. This could result in unrepresentative readings as the patient’s discomfort may be affecting cognitive responses to situations.
• one issue with EEGs

  • Another issue with EEG is that electrical activity is often detected in several regions of the brain simultaneously.
  • Consequently, it can be difficult pinpoint the exact area/region of activity, making it difficult for researchers to draw accurate conclusions.
• strength of ERP

  • ERPs enable the determination of how processing is affected by a specific experimental manipulation.
  • This makes ERP use a more experimentally robust method as it can eliminate extraneous neutral activity, something that other scanning techniques (and EEG) may struggle to do.
• what are post-mortems?

  • A post-mortem examination is when researchers study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage.
• causation of post-mortem

  • The deficit a patient displays during their lifetime may not be linked to the deficits found in the brain. The deficits reported could have been the result of another illness, and therefore psychologists are unable to conclude that the deficit is caused by the damage found in the brain.
  • many extraneous factors that can affect the results. For example, people die at different stages of their life and for a variety of different reasons. Furthermore factors such as age are all confounding factors that make the conclusions of such research questionable.
• strength of post-mortems

  • provide a detailed examination of the anatomical structure and neurochemical aspects of the brain that is not possible with other scanning techniques
  • Post-mortem examinations can access areas like the hippocampus, which other scanning techniques cannot, and therefore provide researchers with an insight into these deeper brain regions, which often provide a useful basis for further research. For example research found higher concentration of dopamine in patients with schizophrenia which has prompted a whole area of research
• limitation of post-mortem

  • While post-mortem examinations are ‘invasive’ there are ethical issues in relation to informed consent and whether or not a patient provides consent before his/her death.
  • Furthermore, many post-mortem examinations are carried out on patients with severe psychological deficits (e.g. patient HM who suffered from severe amnesia) who would be unable to provide fully informed consent, and yet a post-mortem examination has been conducted on his brain. This raises severe ethical questions surrounding the nature of such investigations.