Maguire (contemporary study) Flashcards
What part of the brain does this study investigate?
The hippocampi
Hippocampi structure
Bilateral (1 for each hemisphere)
Contains a posterior (back), main body and anterior (front)
Main function of hippocampi
Helps us to navigate known environments by holding spatial memory of that area
2 background research to this study
Migration seasons for birds mean hippocampus volume increases: does it occur in humans if we require more spatial memory?
Differences across various brain structures exist dependent on people with different skills: did brain change in response to environmental changes of learning skill or were they born with this brain thus more predisposed to taking up the skill?
Who was chosen to be investigated in this study and why?
London taxi drivers because they have to pass a test called ‘the knowledge’
Memorisation of streets and street names in London: compared to average person their spatial memory demand is higher so we can investigate neuroplasticity within them
Aims
Investigate differences in volume of hippocampi London taxi drivers vs not London taxi drivers
Investigate functions of each section of hippocampus
Correlational analysis if there is pos correlation between time spent as taxi driver to volume of hippocampi
Sample of taxi drivers
16 men who had passed the knowledge and 1.5 years experience as a driver
Sample method for taxi drivers
Self selected from radio adverts and contacting the taxi company
Sample of control group (non taxi driver)
50 male MRI profiles from UCL neurology department
Sample method for control group
Opportunity: these are MRI scans of men who happened to be scanned
Controlling for participant variables
Across each group: all men, all right handed, all had healthy neurological profiles, all aged 32-62
What type of experiment is this?
A quasi experiment because the naturally occurring IV is whether someone is a taxi driver and learnt the knowledge compared to someone who is not
Experimental design
Independent measures because we cannot manipulate the IV for participants to go through both conditions and be compared against themselves
What type of MRI scan was used?
Structural MRI scan
Main procedure of the study
Taxi drivers had structural MRI scan and their profiles were compared to MRI scans selected from control group
Analysis of MRI scans
Pixel counting
Voxel based morphometry
Pixel counting
Counting pixels of a 2D cross sectional area of hippocampus sections
voxel based morphometry
3D measurement of volume of grey matter done by computer
How were the analysis of hippocampus done and why is that a strength?
Done by researchers blind to who the profile belonged to
This decreases researcher bias as they will provide objective measurements that isn’t affected by their own interpretation thus increases validity
Checking for concurrent validity
We use the pixel counting older method to check the results of VBM (new) are consistent, thus an accurate measurement of volumes of hippocampus
Results for main procedure analysis of MRI profiles: hippocampus posterior
A significantly higher difference was found in grey matter volume of the posterior hippocampus in taxi drivers compared to the non taxi drivers
Results for main procedure analysis of MRI profiles: hippocampus anterior
Significantly smaller in taxi drivers compared to in the control
Results for main procedure analysis of MRI profiles: hippocampus body
No difference in hippocampus body volume across the 2 groups
What can we conclude from the main procedure?
Differences in volume of the parts of the hippocampus in taxi drivers compared to non taxi drivers: taxi drivers had larger volume in posterior compared to control but a smaller volume of anterior
Body stated constant thus the increase in posterior was offset by decrease in anterior
Differences in function of hippocampus
Correlational study purpose
To investigate if there is correlation between volume of the hippocampus parts and time spent as a taxi driver
What type of study was the correlational part?
A cross sectional study: type of snapshot study
Where we took a snapshot of the MRI scans of taxi drivers of increasing years of experience and compared them against each other to show a change in years spent as taxi driver (rather than the same person)
What did the correlation find?
Positive correlation between time spent as taxi driver and volume of posterior hippocampus volume
Negative correlation between time spent as taxi driver and volume of anterior hippocampus volume
Conclusions from correlational analysis
Confirms brain changed in response to environment (longer time spent demanding spatial memory) so shows evidence for brain plasticity
Rather than people born with this structure of hippocampus are predetermined into becoming taxi drivers
Differences in function of anterior vs posterior hippocampus
Posterior holds spatial memory of previously learnt areas
Anterior works in learning new spatial memory and navigating unfamiliar environments
Small anterior effect on taxi drivers
Have difficulty with spatial memory tasks of new and unfamiliar tasks
