Maguire

Maguire

1. Background

   • Humans and mammals have 2 hippocampi; one in each side of the brain. the major functions of the hippocampi is to do with memory and spacial navigation (this is the ability to navigate from place to place, without physically doing so).
   • Maguire wanted to investigate if experience or need can change our hippocampus to allow us to use spacial navigation more readily.

2. Aim

   • Investigate wether changes could be detected in the brain of humans who have extreme experiences of spacial navigation (taxi drivers)
   • Maguire hypothesised that if there were any significant differences found in the brain of those who rely heavily on spacial navigation, these differences would be found in the hippocampus. (In size, shape)
     • He also assumed that the hippocampus has 'Plasticity'- the ability for the synapses in the brain to strengthen and weaken over time due to learning and experience.

3. Sample

   • The sample was London black cab drivers. they were all aged 32-62 years and must have been driving at least 18 months. They were all right handed. This is because it is believed that what hand you write with affects the way your brain is wired and therefore this could affect results.

4. Method & Design

   • the design can be thought of as an independent measures design as comparisons were made between the groups. (Taxi driver and non-taxi driver. there was also a correlational analysis of the data to show to what extent the shapes and sizers differed from one another.
   • the method was a quasi method as the IV was not manipulated by the experimenter (wether the participants were taxi drivers or not)
   • MRI scans were used to collect 2 types of data: VBM (3D imaging) and Pixel counting (2D imaging)
     • they were measuring a variable from a no. of different angles

5. Results

   • Analysis of the scans was conducted using the VBM technique. These showed that there was a significant increased the volume of the posterior of the hippocampus in the taxi drivers condition compared to the non-taxi drivers.
     • The overall volume is the same, but the non taxi drivers have a larger anterior and smaller posterior and the taxi drivers are the opposite.
   • Results also showed that there was a significantly increased volume in the anterior hippocampus in the non-taxi drivers than in the taxi drivers. No other significant differences were found.
   • the second analysis (only on cab drivers) showed that over time, the hippocampus increased in size. This is a positive correlation.

6. Evaluation

   • Strengths of using MRI scans:
     • Cannot have demand characteristics as you cannot change the size and shape of your hippocampus. This gives accurate results that display true representations. Comparisons can then be made and the results can be statistically analysed.
   • Weaknesses of using MRI scans:
     • time consuming and expensive- meant that they could only have a small sample of 16 people. This means that the sample is non representative of all non-taxi driver and taxi drivers.
   • useful applications- huge surge in the help that those suffering with epilepsy can receive due to the knowledge of brain plasticity that enables it to adapt.
   • cannot generalise as the sample is small and al males that were right handed. Very limited knowledge.