Investigating the brain

• 4 types of measurement

  • FMRI
  • EEG
  • ERP
  • Post-mortem
• How does FMRI measure brain activity?


  • Detects changes in blood oxygenation and flow as a result of neural activity
  • Brain area more active= more oxygen consumption, blood flows to area to meet demand (HAEMODYNAMIC RESPONSE)
  • Brightness shows neural activity and blood flow
  • Produces a 3d image
  • Brain activity measured when ppt is engaged in a task
• How does EEG measure brain activity

  • Records tiny electrical impulses produced by brain's activity
  • Measured via electrodes attached to skull cap
  • Recording represents brainwave patterns generated from neuron action
  • Often used as a diagnostic tool, arrhythmatic patterns of activity may indiciate neurological abnormalities (e.g. epilepsy, seep disorders)
• How do ERPs measure activity in the brain?

  • Event-related potentials
  • Measures brain's electrophysiological response to a specifc sensory/cognitive/motor event
  • Isolated through statistical analysis of EEG data, filters the response relating to task response
  • General measure of activity
• How does a post-mortem study, study the brain?

  • Analysis of brain after death
  • Likely ppts have had a rare disorder or neurological deficit
  • Areas are examined to establish likely cause
  • Can be compared to neurotypical brain to compare and assess effects of abnormalities
• Positives using FMRI

  • Non-invasive and no radiation involved
  • Risk-free
  • High spatial resolution, clear image to easily identify localisation of function and derive patterns/correlations
  • High value evidence, systematic and provides empirical data = high reliability
  • Captures dynamic brain activity as opposed to pure physiology (MRI)
• Negatives/limitations using FMR

  • Low temporal resolution, 2s lag time between neural event and signal on activation map, may decrease reliability of findings
  • Expensive, may result in reduced sample size meaning less variation and empirical evidence to support theories, explanatory ability may be limited alongside ecological validity
• Strengths of using EEG

  • Aid in diagnosis of conditions as random bursts of arrhythmic activity could be identified (e.g. epilepsy)
  • High temporal resolution, accurately detecs brain activity at the resolution of a millisecond, decreases impact of extraneous variables, easy to connect IV and DV effects
• Limitations of EEG

  • Generalised nature, information received is not based off a specific area, focused on global activity of neurons, therefore cannot pin-point exact source of neural activity and may be less accurate = lack of generalisability
  • Poor spatial resolution, pattern is a sum of neurons in cortex
  • Cannot detect deep activity, only surface level, limits explanatory ability
• Strengths of ERPs

  • high temporal resolution, ERPs are derived from EEGs, results in further specification of recorded data that raw EEGs can't achieve, high validity
  • Widespread use and implication, can measure cognitive functions and deficits
  • e.g. identified the P300 component in allocation of attentional resources and maintenance of memory -> likely EEG could not do this alone
• Limitations of using ERPs

  • Lack of standardisation in methodology between research studies, therefore hard to confirm findings and questions overall reliability of findings
  • Hard to eliminate background noise/extraneous material to establish pure ERP data, may affect overall validity of findings and conclusions derived
• Strengths of post-mortem

  • Vital in providing a foundation for early understanding of key processes in the brain
  • E.g Broca and Wernicke's area as language centres, improves overall medical knowledge and helps generate hypotheses for further study