Maguire

• Aim 


  To investigate the role of the hippocampus in navigational and spatial skills and the extent to which the brain shows changes when exposed to extensive navigational experiences

  Correlation between the length of taxi-driving experience and volume of grey matter
• Background 


  Lee et al found the hippocampus in birds and mammals retained its ability to make new cells when seasonal behaviours occur such as homing

  The hippocampus grew more cells and increased in volume
• Design 


  Independent measure

  if they were a taxi driver or not
• Method 


  Quasi experiment as the job role was naturally occurring

  Also involves correlational analysis
• IV

  Taxi driver or not

  Matched on age, gender and handedness
• DV


  Hippocampal volume of the left and right hippocampus

  in 2d and 3d pictures
• Sample


  16 licensed London Taxi Driver (at least 1.5 years experience)

  Right handed

  Aged between 32 and 62

  Average training time was 2 years

  Healthy medically
• Sample - Controls 


  50 participants were chosen from the structural MRI scan database at the same unit where the taxi drivers where scanned

  All male

  Non were taxi drivers

  Right-handed

  Aged between 32 and 62
• Materials 


  Scans were analysed using 2 tecniques ...

  VBM - grey matter volume

  Pixel counting - 2D measure of the area
• Procedure 


  A structural MRI produced a 3D image of the brain

  Pixel counting used 26 slices of the scan

  6 Posterior, 6 Anterior and 12 for the main body of hippocampus
• Procedure - VBM

  Identified the density of grey matter in different parts of the brain

  Grey matter is dense neural connections associated with higher order thinking
• Procedure - VBM


  Identified the density of grey matter in different parts of the brain

  Grey matter is dense neural connections associated with higher order thinking
• Procedure - Pixel counting

  Pixels were counted on a photographic 'slices' to calculate the volume

  The person counting the pixels was blind to who the brain belonged to

  Pixels were counted for the anterior, posterior and main body on 16 controls
• Results

  Volume - Taxi drivers has greater volume in their posterior right hippocampus (VBM)

  Controls has greater volume in the anterior hippocampus and main body

  No significant difference in the overall volume of hippocampus

  Correlation - comparison of length of driving experience with the measure of grey matter volume of taxi drivers showed a significant positive correlation for the right posterior hippocampus
• Conclusions

  Taxi driver hippocampi may have changed as a result of studying for the 'knowledge' thus shows plasticity

  Supports the idea of plasticity can occur locally in the brain in response to prolonged environmental stimuli