maguire

• What was the aim?


  To show that the hippocampus in a human brain is the structure associated with spatial memory and navigation
• What was the sample?


  Experimental group:

  -16 taxi drivers

  - all healthy

  - all male, London taxi drivers

  - all right handed

  -mean experience of 14.3 years as taxi drivers

  
  

  Control group:

  - 50 control ppnts who were chosen from the same MRI database in the same unit as the taxi drivers

  -Matched on: health, handedness (right-handed), sex (male) and age
• What was the method?


  Experiment and also a correlation study

  Used matched pairs design

  IV- taxi driver or not

  DV- volume of hippocampus

  Correlation was between the length of time as a taxi driver and volume of hippocampusThe correlation
• What was the procedure?


  All MRI scans analysed in 2 ways:

  1. VBM- automatic procedure where the brain size was eliminated as a variable and identifies the difference in grey matter density in different regions of the brain. (was done with all 50 control and 16 taxi drivers)

  2. Pixel counting- compares the volume of the body, anterior and posterior cross sections in hippocampus of taxi drivers (was done with 16 taxi drivers and 16 of the 50 controls)

  This was done by 1 analyst who was an expert and was blinded to if the scan was of a taxi driver or a control

  
  

  For the experiment the volume of grey matter in the hippocampus was compared in taxi drivers vs non

  For the correlation the length of time as a taxi driver and the volume of the hippocampus were investigated
• What were the results?


  Anterior hippocampus:

  VBM- there was more grey matter volume in the control group's left and right anterior hippocampus

  Pixel- the volume of the anterior right hippocampus was greater in the control than taxi drivers

  
  

  Posterior hippocampus:

  VBM- there was more grey matter volume in taxi driver's left and right posterior hippocampus

  Pixel- the volume of the posterior hippocampus was greater in taxi drivers than non

  
  

  Correlation:

  - Positive correlation between length of time as a taxi driver and the volume of their right posterior hippocampus

  - Negative correlation between length of time as a taxi driver and anterior hippocampus volume
• What were the conclusions?


  There are structural differences in the hippocampi of taxi drivers in London vs non-taxi drivers in London

  The professional dependence on navigation in taxi drivers in London is associated with a redistribution of grey matter in the hippocampus

  The changes in the re-arrangement of the hippocampal grey matter acquired (due to nurture)

  Findings suggest local plasticity in the structure of the human brain to adapt to prolonged environmental stimuli