APFCC+-+Maguire+et+al

=APFFC: Maguire et al=


 * Theorist ** : Maguire et al
 * Study ** **of**: Spatial Memory
 * Year ** : 2000

The structural changes in brain size and shape in London Taxi Drivers.
 * Summary: **

To investigate if there was structural changes in the hippocampi of taxi drivers
 * Aim ** :

Research Question: That the hippocampi on London Taxi drivers will be structurally different to the hippocampi in non-taxi drivers. Method: Natural Experiment IV: Taxi driver or not DV: Structure and Volume of hippocampi 16 right handed male taxi drivers Matched pairs
 * Procedures: **

MRI scans were taken of 50 healthy right-handed male, non taxi drivers to establish a base data point.

The matched pairs were then scanned and compared to the base data point.

The expert conducting the analysis didn’t know whether the MRI was taxi driver or not. (single blind)

Increased volume of grey matter in both the right and left hippocampi of taxi driver brains. There was a correlation in the increased volume and time spent as taxi driver. Taxi drivers had greater volume in the posterior hippocampus but non-taxi drivers had greater volume in the anterior hippocampus.
 * Findings: **

It was found that the brain structure isn’t fixed at birth and instead is shaped by your environment. That the mental map of the city of London is stored in the posterior hippocampi.
 * Conclusions: **

Usefulness Evidence that normal activities can induce changes does have implications for rehabilitation after injury.
 * Criticisms: **

Strengths Has ecological validity. It is hard to find people without any spatial awareness. Quantitative Data - fact objective, scientific and replicable. Limitations

Maguire et al (2000)

1. Licensed London taxi driver with a minimum of 18 months job experienced (average of about two years acquiring the knowledge). 2. Non-taxi drivers (control group) Dependent variable: volume of hippocampus (including their anterior, body and posterior sections). Participants: 16 healthy, right-handed, male, London taxi drivers. Average age 44, matched in helath, handedness, sex, average age and age range. Procedure:
 * Aim :
 * 1)  Navigational experience and the role played by the hippocampus in humans.
 * 2)  Whether the healthy human brain can undergo 'plastic' (structural) changes in response to extensive navigational experience.  ||
 *  Procedures:
 * 1)  Natural experiment, independent measures/matched pairs.
 * 2)  Independent variable: Amount of navigational experience (tested in two conditions)
 * 1)  Structural MRI: scans of taxi drivers and non-taxi drivers were analysed.
 * 2)  VBM: an automatic procedure that 'normalised' the scans to a template (to eliminate overall size of brain as a variable) and compared the taxi driver's brains with a control group of 50 non-taxi drivers to see if any differences in structure were to be found anywhere in the brain.
 * 3)  Pixel counting: experienced observer (not aware of identities of the participants or the VBM results) compared the volume of the anterior, body and posterior cross-sections of the taxi driver's hippocampus with those of a precisely matched control group.  ||
 *  Findings:
 * 1)  VBM analysis : despite no significant differences elsewhere in the brain between the experimental and control group, the taxi drivers had significantly increased grey matter volume in the right and left posterior hippocampus compared to controls.
 * 2)  Pixel counting: despite no significant differences in overall volume of hippocampi between the two groups:
 * 3)  Taxi drivers had significantly larger volume in the posterior hippocampi compared to controls.
 * 4)  Controls had a significantly larger volume in the anterior hippocampi compared to taxi drivers.
 * 5)  Correlations: a significant positive correlation was found between time as a taxi driver and right posterior hippocampal volume (but a negative one for the right anterior section).  ||
 *  Conclusions:
 * 1)  Human spatial representations and navigational experience are stored in the posterior hippocampus.
 * 2) <span style="direction: ltr; font-family: Arial; 16px list-style-type: disc; margin-bottom: 0in; margin-bottom: 0px; margin-left: 0.167in; margin-top: 0in; margin-top: 0px; unicode-bidi: embed; vertical-align: middle;"> The structural rearrangement of the hippocampus in the taxi drivers reflects, rather than causes, the amount of navigational ability.  ||
 * Evaluation:
 * 1) <span style="direction: ltr; font-family: Arial; 16px list-style-type: disc; margin-bottom: 0in; margin-bottom: 0px; margin-left: 0.167in; margin-top: 0in; margin-top: 0px; unicode-bidi: embed; vertical-align: middle;"> The healthy human brain can change in structure in response to environmental stimulation. This has implications for rehabilitation after brain damage, although this study only applies to the hippocampus.
 * 2) <span style="direction: ltr; font-family: Arial; 16px list-style-type: disc; margin-bottom: 0in; margin-bottom: 0px; margin-left: 0.167in; margin-top: 0in; margin-top: 0px; unicode-bidi: embed; vertical-align: middle;"> The methods of measurement were objective and well-controlled by computer or blind assessment.
 * 3) <span style="direction: ltr; font-family: Arial; 16px list-style-type: disc; margin-bottom: 0in; margin-bottom: 0px; margin-left: 0.167in; margin-top: 0in; margin-top: 0px; unicode-bidi: embed; vertical-align: middle;"> The study does not indicate how the brain changes occur.  ||