Ways of studying the brain

• Describe what is meant by post mortem examinations. Why are they useful?

  • Examining the actual physical brain to identify lesions in abnormal cases, after a patient has died
  • can be used to discover more about psychiatric disorders (eg schizophrenia)
  • can be used to analyse brain structures involved in memory
  • Used to discover Broca's area
• What did Paul broca discover?

  • Studied a patient he referred to as Tan
  • Tan was subsequently found using post mortem examinations, to have a legion in his brain now known as Broca’s area which was important for speech production
• Describe what fMRI involves

  • Measures changed in brains activity while performing a task by measuring changes in blood flow.
  • if the brain is more active, there’s an increased demand for oxygen and high blood flow means high brain activity in that area
  • Researchers produce maps showing which areas of the brain are involved in a particular mental activity
• Describe what EEG involves

  • signals are graphed over a period of time
  • Data is used to detect brain disorder using alpha/beta/delta waves. To do this, electrodes are placed on the scalp to detect electrical changes from brain cells
• Describe what ERPs involve

  • Take raw EEG data and uses it to investigate cognitive processes of a specific event.
  • many presentations of the stimulus and response are averaged together to filter out brain activity not related to stimulus
  • Sensory ERPs- reflect initial response to physical characteristics of the stimulus
  • Cognitive ERPs- demonstrate info processing
• Two advantages and disadvantages of fMRIs?

  • 😊 non-invasive, no instruments into brain
  • 😊 more objective and reliable than verbal feedback. A way of investigating psychological phenomena
  • ☹️ not direct measure of neural activity- only measures blood flow, not truly quantitative
  • ☹️ Focuses only on localised brain activity- doesn’t regard communication among the different regions
• Two advantages and disadvantages of EEG?

  • 😊 records abnormal brain activity in real time rather than a still image of the passive brain
  • 😊 useful in rapid diagnosis- epilepsy, can tell whether someone experiencing seizures has epilepsy/not
  • ☹️ doesn’t reveal what's going on in deeper brain regions like hypothalamus
  • ☹️ neighbouring electrodes pick up electrical activity so can’t pinpoint exact source of activity
• Two advantages and disadvantages of ERP?

  • 😊 continuous measure of processing in response to a particular stimulus, therefore possible to see how processing is affected by experimental manipulation
  • 😊 measures processing of stimuli even in absence of a behavioural response
  • ☹️ so small and difficult to pick out from other electrical activity- requires many trials to gain meaningful data
  • ☹️ only sufficiently strong constant changes across the scalp are recordable, deeper electrical activity isn’t
• Two advantages and disadvantages of Post mortem examinations?

  • 😊 more detailed examination of anatomical and neurochemical brain aspects
  • 😊 Central role in understanding of the origins of schizophrenia- evidence in changes in neurotransmitter systems
  • ☹️ people die in various circumstances, can influence the post mortem brain
  • ☹️ retrospective as person is already dead. researcher unable to follow up on anything that arises after the examination concerning relationships between brain abnormalities and cognition
• Differences between fMRI and ERPs?

  • fMRIs have poor temporal resolution, whereas EPRs have good temporal resolution
  • fMRIs provide indirect measure of neural activity whereas ERPs offer a direct measure of neural activity
  • fMRIs are more expensive than ERPs
  • Different methodology- fMRIs measure changes in blood oxygenation as a measure of neural activity whereas ERPs measure electrical activity via electrodes, detecting brain waves triggered by certain events
• similarities between fMRIs and ERPs?

  • both act as a measure of brain activity related to specific events
  • both are non-invasive