Maguire

• Background

  • Taxi drivers brains grow on the job, grey matter enlarges and adapts to help them store a more detailed map of the city.
  • They have a larger hippocampus which is the part of brain associated with navigation
  • Hippocampus located in the limbic system and there's evidence to suggest that the hippocampus plays a major role in short term memory and spatial navigation
  • plasticity - changes occur in the organisation of the brain as a result of experience
• Aim

  Investigate whether changes could be detected in the brains of London taxi drivers and to further investigate the functions of the hippocampus in spatial meaning
• Design

  • Quasi experiment
  • compare data of taxi drivers to non taxi drivers
  • Made correlational analysis as they are investigating relationship between MRI scans and length of time being taxi drivers
• Participants

  16 healthy, right handed male London taxi drivers

  mean age - 44

  Had all been licensed taxi drivers for at least 1.5 years

  Average time spent training was 2 years

  Compared to control groups of 50

  Ensured there was an even spread of participants in each decade
• Procedure

  • collected using MRI which collects collects data about structure of the brain
  • MRI scans expose the brain to a strong magnetic field to produce detailed pictures
  • Data measured using2 techniques VBM and Pixel counting
• Voxel Based Morphometry

  Used to measure density of grey matter

  provided 3D measurement of volume of an area
• Pixel Counting

  • carried out on scans of the 16 taxi drivers and 16 age matched controls out of the 50 control group
  • Consists of counting the pixels in the images and the counting is carried out by a researcher who wasn't aware of which group they were apart of
• Results

  • posterior hippocampi (back) of taxi drivers was significantly larger than control group.
  • Anterior hippocampi was larger in control subjects
  • VBM - significantly increased grey matter found in the brains of taxi drivers in posterior and less in the anterior
• Explanation of results

  • Hippocampus stores spatial memory
  • Demonstrates plasticity of the hippocampus in response to environmental demands
  • Argues posterior and anterior have different roles. Posterior - previously learned spatial information stored
  • Anterior - more involved during encoding of new environmental layouts
  • Right side holds mental maps and the left stores memory of people and events
• Strengths

  • Vast amounts of quantitative data relating to volume and size of hippocampus
  • employed many controls
  • Ethical study
• Limitations

  • Difficult to make conclusion from quasi experiment because the differences may not have been because of IV. eg , people have large hippocampus and therefore have good navigational skills and so were attracted to job of taxi driver
  • Being scanned in MRI is not ecologically valid
  • Participants were all able and right handed