Ways of studying the brain

• Brain scanning is used to study the brain, there are four brain scanning techniques
• CAT (Computerised Axial Tomography), this techniques uses an x-ray beam to produce a picture of the brain that shows the physiology of the brain, this is not a moving picture, but can show lesions on the brain
• PET (Position Emission Tomography), this technique involves injecting the patient with a radioactive glucose to produce a moving picture of the brain. The glucose goes to the seas of the brain with the most activity and so this is able to be picked up in the scan
• MRI (Magnetic Resonance Imaging), this technique records the energy produced by molecules of water once the magnetic field is reduced, it is a still picture produced
• fMRI (Functional Magnetic Resonance Imaging), this technique works in a similar way to MRI's, however, instead of measuring the energy emitted from water, it measures the energy released by haemoglobin and is a moving picture. fMRi is the brain imaging technique which the specification focuses on
• fMRI (Functional Magnetic Resonance Imaging)

  fMRI works by detecting blood flow (oxygenated haemoglobin blood which reacts to the magnets) in the brain

  It uses large magnets to detect oxygenised blood and show deoxygenised blood

  Brain areas that are more active, need more blood flow, this is oxygenised blood

  inactive or less active parts of the brain will show deoxygenated blood

  Active areas can then be compared with areas that are lower in activity and can be shown on the fMRI image
• Strengths of fMRI:

  • Good spatial recognition of 1mm. Precisely identifying active brain regions and patterns of activation over time.
  • It produces a moving picture, which allows comparison over time.
  • It is a non-evasive and safe technique for patients.
• Limitations of fMRI:

  • Expensive and hard to build
  • Participant/patient needs to remain very still throughout and is not allowed to move.
  • Due to availability and funding the sample size is often very small.
• • When studying the brain using EEG, electrodes are placed on the scalp and they record activity in the brain
  • Usually there are between 22-34 electrodes placed on the scalp
  • The electrodes are fitted to a cap and the cap is placed on the participant with conductive gel
  • The electrodes measure the activity of the cells directly below them
  • The activity is displayed in brain waves, which is a series of lines showing distinct patterns
  • The amplitude shows the brain intensity and the frequency shows the speed of activation
  • Giving a picture of the brain activity underneath the electrodes
• ERP (Event-related Potential)

  ERP uses the same apparatus and technique as EEG

  They record when there is activity in reaction to a stimulus

  This stimulus is presented many times

  This provides data using statistical averaging

  The waveform's peaks and dips show exactly when cognitive processes happen in the brain in relation to when the stimulus is presented
• Strengths of EEG & ERP:

  • Both EEG and ERP are cheaper alternatives to studying the brain than brain imaging techniques
  • Both methods are useful to test reliability on self reporting techniques, particularly to avoid social-desirability bias
  • Both have been historically important in understanding the brain and studying it, especially related to sleep and medical diagnosis
  • ERP's allow researchers to isolate and study how individual cognitive process take place in the brain
• Limitations of EEG & ERP:

  • Both methods are only reasonably accurate, which means finer details are missed.
  • Expertise is needed to interpret the outcome from the equipment.
  • Both EEG and ERP are not able to detect activity deep in the brain.
  • Some cognitive process can not be studied using ERP as they are unable to be presented multiple times.
• Post Mortem Dissection

  Post mortem dissections/examinations are when a persons body, including their brain, is examined after they die

  During the examination, brains are precisely cut

  Researchers will examine and dissect brains of individuals who had suffered from trauma or mental illness and compare the brain with someone who had a neurotypical brain

  This allows researchers to identify key function of specific parts of the brain

  Broca's area was discovered by post-mortem dissection
• Strengths of Post Mortem Dissection:

  • Post Mortem dissections have been fundamental in the development of understanding brains and how they function, including understanding localisation of function.
  • The individual is not alive and so cannot experience any discomfort.
• Limitations of Post Mortem Dissection:

  • No brain activity can be measured as the research is conducted on a dead person.
  • Brains could have been affected by the cause of death, effecting the results.
  • It is difficult to compare the brain after death with the functioning prior to death, any relationship found would be correlational and not causal.