Maguire

• Hippocampus is a major structure of the limbic system- involved with behaviours from motivational learning and emotional needs
• Hippocampus- important in laying down new memories found in each hemisphere + important in facilitating spatial memory + navigation- lesions can affect ones ability to remember location of different places and things
• Increased hippocampal volume relative to brain + body size
• Some species hippocampal volume changes in certain seasons
• Not previously seen if differences in brain susceptible to plastic change in response to environmental stimuli - whether human brain responds to spatial and navigational info
• Sample ideal as taxi drivers have to quire spatial and navigational info - wide range of navigational experience allowed for examination of the direct affect of spatial experience on brain structure
• Quasi experiment- IV- ppt being a taxi driver or not

  DV- volume of hippocampi- anterior, posterior + body regions- measured be analysing MRO scans of ppts brains using VBM + pixel counting

  • independent measures and matched ppts used
• 16 taxi drivers- righthanded, male, mean age 44

  -mean time being taxi driver 14.3 years

  -control did not drive taxis- matched for health mean age+ age range
• Scans of control group selected for structural MRI scan data bade at same unit where taxi drivers scanned
• MRI analysed using VBM- normalises scans to a template to eliminate brain size as a variable + identifies differences in grey matter density in different regions of the brain

  -16 taxi drivers compared to 50 non
• Pixel counting- compared volume of anterior, body and posterior cross sections of the drivers hippocampi with those previously matched+ analysed by one person- did not know taxi driver or regular person
• VBM analysis- no significant differences between the groups

  • Taxi had increased grey matter in volume
  • controls greater matter in volume in the right + left anterior hippocampi
• Pixel counting- no significant difference in hippocampal volume

  • taxi drivers greater posterior hippocampal volume
  • Controls greater anterior right hippocampal volume
  • Controls greater hippocampal body volume on right than on left compared to taxi drivers
• Correlations- significant positive correlation between length of time as taxi driver + right posterior hippocampal volume
• Concluded: regionally specific structural differences between hippocampi of London taxi drivers compared to those who don't drive a taxi
• Concluded: professional dependence on navigational skills associated with a relative distribution of grey matter in hippocampus- changes in arrangement of grey matter are acquired
• Concluded: findings indicate possibility of local plasticity in structure of normal human brain allows for adaptation in response to prolonged environmental stimuli