Brain Investigation Techniques

• What are 4 ways of investigating the brain?

  1, Functional magnetic resonance imaging (fMRI) 2, Electroencephalogram (EEG) 3, Event-related potentials (ERPs) 4, Post-mortem examinations
• Which investigating technique is most likely to measure whole brain activity rather than specific areas of activity?

  EEG
• Which investigating technique detects changes in blood oxygenation and flow that occur as a result of neural activity?

  fMRI
• Which investigating technique uses a statistical averaging technique to remove extraneous scan data?

  ERP
• What is a post-mortem?

  Analysis of a person's brain after their death
• What is an advantage of using EEGs over fMRIs?

  EEGs have a high temporal resolution, whereas fMRIs have a poor temporal resolution
• Which investigating technique is a useful diagnostic tool for epilepsy?

  EEGs
• What is an advantage of using a post-mortem over non-invasive techniques (fMRI and EEGs)?

  x Allows a more detailed examination of anatomical and neurochemical aspects of brain that wouldn't be possible with non-invasive techniques x Played central part in early understanding of key processes in the brain before neuroimaging became a possibility.
• What are two limitations of using post-mortems?


  1, Issues with causation - damage may not be linked to deficit under review but to some other trauma 2, Ethical issues of consent from before death
• What is an advantage of using fMRIs?


  x Produce images that have very high spatial resolution (1-2 mm) and clear picture of how brain activity is localised x Non-invasive - no insertion of instruments into the body or exposure to harmful radiation
• Description of fMRI

  x Measures the changes in blood flow in particular areas which shows neural activity when a person performs a task. x When a brain area is more active it consumes more oxygen so there is increased blood flow to this area delivering oxygen. x Deoxygenated and oxygenated haemoglobin have different magnetic qualities and an fMRI scanner can detect this and create a moving 3D image showing which parts of the brain are involved in a particular mental process.
• Description of an electroencephalogram (EEG)


  x Measures general electrical activity in the brain via electrodes that are fixed to the scalp x These electrodes detect activity of millions of neurons, providing an overall account of brain activity.
• Description of event-related potentials (ERP)


  x Are very small voltage changes in the brain that are triggered by specific events or stimuli x This is achieved by isolating EEG data through statistical analysis
• Description of post-mortem examinations

  x Analysis of the brain following a person’s death x Person is most likely to have had a rare disorder or experienced unusual deficits in mental processes or behaviour during their lifetime x Example = Broca’s patient ‘Tan’
• What is a disadvantage of using fMRI


  X Poor temporal resolution - there is a 5-second time-lag behind the image on screen and the initial firing of neuron activity. X Only measures blood flow in brain and cannot hone in on the activity of individual neurons = difficult to tell exactly what kind of brain activity is being represented
• What is an advantage of using an electroencephalogram (EEG)


  x High temporal resolution - every millisecond x Useful in clinical diagnosis - has proved invaluable in diagnosis of epilepsy
• What is a disadvantage of using an electroencephalogram (EEG)


  x Poor spatial resolution - can only detect activity in superficial regions of the brain, and not in deeper regions such as the hypothalamus or hippocampus. x Not useful for pinpointing the exact source of neural activity as electrical activity can be picked up by several neighbouring electrodes.
• What is an advantage of using event-related potentials (ERPs)


  Can measure the processing of stimuli even in the absence of a behavioural response. They make it possible to monitor ‘covertly’ the processing of a particular stimuli without requiring the person to respond to them.
• What is a disadvantage of using event-related potentials (ERPs)

  x In order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated and this may not always be easy to achieve. x Lack of standardisation in methodology between different research studies - makes it difficult to confirm findings.