Maguire et Al

• Name of study?

  ”navigation-related structural changes in the hippocampi of taxi drivers“
• aim?

  • to show the ability of the brain to change and adapt as a response to learning
• method?


  • lab experiment
  • independent groups
  • quasi design - occur naturally (right handed males)
  • variables
• DV?


  • structural changes
• IV?


  • taxi driver or not
• CV?


  • 16 right handed males
• participants?


  • 16 right handed males
  • aged 32-62
  • all licensed for 1.4-42 years
  • at least 2 years of knowledge
  • all healthy
• control group participants?


  • not taxi drivers
  • 50 right handed males
  • aged 32-62
  • all healthy
  • all had been previously scanned and data on MRI database (brain scan for structure)
• what were the brain scans analysed by using?

  • 24 slices of hippocampus
  • 6 posterior
  • 6 anterior
  • 12 hippocampal body
• what did the brain scans look at?

  • all 66 scans looked for 24 slices by conditional blind analyists (didn’t know if scan was from taxi driver or not)
  • grey matter
  • pixel-counting
  • VBM (voxel based morphometry)
• what is grey matter?

  • grey matter = makes up outermost layer of the brain, gets its grey tone from the high concentration of neuronal cell bodies
• what is pixel counting?

  • images analysed by counting number of pixels occupied by hippocampal tissue
  • count converted into grey matter
  • volume corrected for Total Intracranial Volume (brain size)
• what is a VBM?

  • voxel-based morphometry - 3D measurement of grey matter volume
• results?

  • VBM: increases in left and right posterior hippocampal volume in taxi drivers compared to non tax drivers
  • decrease in left and right hippocampal volume in taxi drivers compared to non taxi drivers
  • no difference in overall volume in either taxi or non taxi drivers
  • pixel counting = non taxi drivers had higher volume in right anterior than left
• what did the scatter graphs show?

  • posterior graph = positive correlation - as time as taxi drivers increase, volume of grey matter in posterior increases
  • anterior graph = negative correlation - as time as taxi drivers increase increases, volume of grey matter in anterior decreases
• conclusions?

  • environmental stimulation causes a shift in hippocampal volume
  • brain changes in response to demands
  • brain plasticity
  • no critical period
  • posterior - uses previously learnt information
  • anterior - learning new experiences
  • right hemisphere correlated more closely to time as taxi drivers increase, because right hippocampus is involved in mental maps
  • left hippocampus is involved in memories or events
• what does posterior use?

  • uses previously learnt information
• what does the anterior involve?

  • learning new experiences
• what is right hippocampus involved with?

  • mental maps
• what is left hippocampus involved in?

  • memorise or events
• application?


  • if brain plasticity can occur in the hippocampus, can it occur in other areas of the brain?
  • if environmental stimulation can result in brain plasticity, then can we encourage brain plasticity?
• type of data?


  • quantitative dat - statistical analysis, measurements of length and volume are highly objective
• ethics?


  • informed consent
  • right to withdraw
  • control group weren’t given unnecessary brain scans as their data was retrieved from an existing store, avoids potential distress
• validity?


  • concurrent validity - VBM and pixel-counting both showed similar results
  • ecological validity - participants didn’t carry out any tasks
• reliability?


  • collection of quantitative data can be replicated to check for reliability
  • consistency is achieved in the way in which the hippocampal volumes were recorded from the brain scans - experienced individual assessed all the images
• sample?


  • only right handed males were used - limits generalisability
  • Possible that females and males brains may respond differently to environmental demands (gender bias)
• ethnocentrism?


  • yes: knowledge possibly enhances taxi driver ability to respond to environmental demands
  • No: anatomy of the brain and response to environmental demands are species specific
• psychology as a science?

  • control of variables and use of scientific equipment
• nature vs nurture:


  • nurture: environmental demands placed on spatial memory of London taxi drivers to increased hippocampal volume (posterior) brain plasticity
• usefulness?


  • MRI scans only show the differences in brain structure not the cause of changes - limits usefulness
  • rehabilitation of people with brain damage - brain plasticity seen in hippocampus of taxi drivers can be possibly extended to other regions of the brain, using suitable environmental cues to cues to stimulate them and cause positive change