ways of studying the brain

• Post mortem

  An examination of the brain after death

  1. Study individuals behaviour whilst they are alive 
  2. Study the brain after death, looking for abnormalities that would explain an abnormal behaviour -compared to normal brain 
  3. Correlation between abnormal behaviour and area of brain

  Eg. Tan and Broca
• Strengths of post mortem

  • allows researchers to reach and investigate into deeper areas of the brain
  •   eg.hippocampus and hypothalamus which aren’t possible with other techniques 
  • More detailed being able to examine brain firsthand 
  • Harrison suggested they have played a key role in finding origins of schizophrenia- been able to see structural abnormalities 
• Limitations of post mortems

  • Cause and effect 
  • Confounding factors: Different circumstances and levels of disease they die from can affect the brain other than behaviour trying to be investigated 
  • As well as length of time between death and the examination,drug treatments and age 
• Fmris

  Functional magnetic resonance imaging 

  • uses magnetic field and radio waves to monitor blood flow; 
  • Oxygen in bloodstream is attached to haemoglobin and becomes deoxygenated when oxygen is released for use
  • Deoxygenated haemaglobin has a diff magnetic quality which can be detected and used to create a moving 3d map of the brain
  • The change of energy released by haemoglobin reflects to activity of the brain 
  • More flood flow=more need for oxygen=more activity
  •  activity in regions of interest can be compared during a baseline task and during a specific activity
• strengths of fmris

  • An advantage of fMRI is that is non-invasive. Unlike other scanning techniques eg pet it doesnt use harmful radiation 
  • fMRI scans have a spatial resolution of approximately 1-2 mm which is significantly greater than the other techniques (EEG, ERP, etc.) Consequently, psychologists can determine the activity of different brain regions with greater accuracy 
• Limitations 

  • 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). Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity
  •  fMRI scans simply measure changes in blood flow and not a direct measure of neural activity meaning it is difficult to establish a causal relationship between a brain region and function 
• describe process of EEGs

  • Electrodes placed on the scalp detect small electrical changes resulting from neuronal activity of brain cells directly below
  •  differing numbers of electrodes can be used depending on focus of the research 
  • Signals graphed over a period of time into wave pattern indicating the level of activity in the brain.
• There are four types of EEG patterns

  • alpha waves,
  • beta waves,
  • theta waves
  • delta waves.
• Each of these patterns has two basic properties that psychologists can examine:

  • Amplitude: the intensity or size of the activity
  • Frequency: the speed or quantity of activity
• Strengths

  • 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 of different psychological phenomena
  • good temporal resolution: it takes readings every millisecond, meaning it can record the brain’s activity in real time =accurate measurement 
• Limitation 

  • one disadvantage of EEG/ERP is that these techniques have poor spatial resolution.
  • , 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
•  use similar equipment to EEG, electrodes attached to the scalp. However, the key difference is that a stimulus is presented to a participant (for example a picture/sound) and the researcher looks for activity related to that stimulus. Many presentations of stimuli and averaged
• Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect, and is an important feature of brain scanning techniques. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy
• Temporal resolution refers to the accuracy of the scanner in relation of time: or how quickly the scanner can detect changes in brain activity.
• a stimulus is presented and they look for activity related to that stimulus

  key difference with erp