Background & Aim
- Does the structure of your brain change in response to environmental demand?
- The aim was to find out whether changes in the brain could be detected in those with extensive navigation experience.
- Based on research suggesting that the role of the hippocampus is to facilitate spatial memory (navigation).
- Maguire hypothesised that the hippocampi in London Taxi drivers will be structurally different to the hippocampi in non-taxi drivers.
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Method, Procedure & Controls
- Natural/Quasi experiment: Independant Design/Matched Pairs Design.
- Correlation: Between length of time taxi-driving and volume of grey matter.
- Participants; Group 1:
- 16 right handed
- male taxi drivers
- average age 44
- all liscensed more than 18 months
- average time as taxi driver 14.3 years.
- Group 2:
- 50 right handed
- age matched
- non taxi-drivers - chosen from a database at the same unit where the texi drivers were scanned.
- IV: London Taxi driver (brain) or Non Taxi driver (brain)
- DV: Structure and volume of hippocampi
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Method, Procedure and Controls (2)
- Image acquisition: Structural MRI scans were obtained of the 50 non-taxi drivers to establish a comparison database of 'average hippocampi'.
- The taxi drivers also scanned.
- Analysis: Voxel-based morphology (VBM) used to measure the density of grey matter in the brain.
- VBM provides 3D measurement of volume of an area.
- Analysis: Pixel counting was carried out on 16 taxi-drivers and 16 age-matched non taxi drivers.
- It is a 2D measurement of an area.
- The scan was seperated into 26 slices.
- Control: The expert conducting the analysis did not know whether MRI scan was of taxi driver brain or not.
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- The Voxel Based Morphology (VBM) found that taxi drivers have a greater volume of grey matter volume in their right posterior hippocampus.
- Whereas, the control group had a greater volume of grey matter in their anterior hippocampus.
- The pixel counting analysis supports these results.
- Positive correlation: As the length of time a taxi driver had been driving increased, the volume of grey matter in the posterior hippocampus also increased.
- As the length of time a taxi driver had been driving increased, the volume of grey matter in the anterior decreased.
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Conclusions & Implications
- The structure of the brain changes in response to environmental demand.
- The mental map of the city of London is stored in the posterior hippocampi in taxi drivers.
- Normal activity can induce changes in the structure of the brain and that this has many implications for rehabilitation after brain injury.
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