Maguire

• background

  • damage to the hippocampus has resulted in failure to form new memories
  • patient HM had surgery to reduce epileptic seizures which meant removing a large portion of tissue, could not form new memories
• aim - investigate whether changes in the volume of grey matter can be detected in the brains of people with extreme experiences of spatial navigation
• method

  • quasi experiment
  • matched pairs design - matched on handedness, age, gender
• voxel-based morphology - allows investigation of difference in brain structure and function, allows us to calculate volume of grey matter
• pixel counting - counting the number of pixels in an image to determine the size of the structure
• sample

  • 16 male taxi drivers who passed the knowledge
  • control group 50 males
  • all 50 used in VBM and 16 in pixel counting
• results

  • taxi drivers showed an increase in volume of grey matter in the posterior hippocampus compared to controls - VBM
  • no significant differences in number overall volume - pixel counting
  • as time as a taxi driver increases, the volume of grey matter in the posterior hippocampus increases
• conclusions

  • the hippocampus is plastic as it is always increasing regardless of age
• strength

  • reliable
  • objective
• weakness

  • not representative, no women taxi drivers
  • quasi experiment reduces the repeatability
• similarities bc

  • both opportunity sampling
  • both ethical
• differences bc

  • bc = lab experiment, m = quasi
  • bc = independent measures design, m= matched pairs design
• relate to biological area

  assumption - measured scientifically

  • uses an MRI machine and objective measures e.g, VBM
• relate to key theme brain plasticity

  found that as time as a taxi driver increased so did the volume of grey matter in the posterior hippocampus and therefore the brain is plastic as it is constantly adapting