Maguire

Sample

Research method

Procedure

Procedure Analysing scans

Findings of experiment

Findings of correlation

Aim

Conclusions

to investigate the role of the hippocampus in navigational and spatial skills in London taxi drivers, and to see the extent to which the brain shows changes (plasticity) when exposed to extensive navigational experience

Hypotheses

There will be a difference in hippocampal volume between taxi drivers and non taxi drivers

There will be a correlation between time spent as a taxi driver and hippocampal volume

Taxi drivers- self selecting
Taxi drivers included 16 right handed, male taxi drivers, average age 44, all licensed more than 18 months and had passed the knowledge test. Range of experience 1.5-42 years

Non taxi drivers-opportunity. Control group of 50 right handed, male, non taxi drivers that were all age matched to taxi drivers. Their brain scans were taken from the MRI scan database.

DV:Structure and volume of hippocampi (measured using VBM and Pixel count)

Natural (quasi) experiment which was lab based and used correlation.
Independent measures for the VBM scans
Matched pairs for the pixel counting

IV: London taxi drivers (brains) or non taxi drivers (brains)

Stage 1: MRI scans of 50 healthy, right handed, male, non taxi drivers aged 33-61 were analysed to establish a comparison database of average 'hippocami volume and structure'. Compared to taxi drivers using VBM

Voxel-Based Morphometry
This identifies differences in the density of grey matter in different parts of the brain in MRI scans. Grey matter is associated with higher order thinking

Pixel counting
Pixels were counted on photographic 'slices' made through the brain using an MRI scan.The person counting the pixels was double-blind to taxi driver and aims of study.

Procedure

Data was collected using MRI scans. MRI scans use magnets and radio pulses to measure changes in the oxygen level. Involves magnetic fields rotated around head, producing a 3D picture

Stage 2: MRI scans of brains of 16 taxi drivers and over 16 matched controls (age matched) were analysed using pixel counting.

There are differences in the distribution of grey matter volume, between taxi drivers and non taxi drivers in regions of the hippocampus. Taxi drivers have a greater volume of grey matter in the posterior hippocampus, non taxi drivers have a greater vol of grey matter in anterior hippocampus.

Brain does show plasticity, supported by the results of the correlational analysis which showed that the longer they had been a taxi driver, the greater the volume of grey matter in right posterior hippocampus

No overall difference in volume of hippocampus but there were some regional differences:
1) Posterior hippocampus greater in TD in both left and right hippocampi
2)Anterior hippocampus greater in NTD in both left and right hippocamppi
3)No significant difference in the body of the hippocami between TD and NTD

There was a positive correlation between length of driving experience and grey matter volume of the taxi drivers right posterior hippocampus.


The more experienced the driver is the greater the grey matter vol in right hippocampus.


Negative correlation between length of driving experience and grey matter vol of the TD anterior hippocampus.