Navigation-Related Structural Change in the Hippocampi of Taxi Drivers

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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A Commentary of …

Navigation
-
Related Structural Change in
the Hippocampi of Taxi Drivers



Maguire, E.A., Gadian, D.G., Johnsrude, I.S., Good, C.D.,
Ashburner, J., Frackowiak, R.J., and Frith, C.
D
.

MARRY


Presented by Group B5:


Nidhi Bhusha, Marry Fernam, Amina Nawaz,
Rachel Wallace and Rory Wasserman




Commentary Presentation…

Overview

MARRY




Key Terms




Positive Comments




Criticisms




Follow
-
up Studies




Class Discussion




Summary of Study…

Key Terms

MARRY


The Knowledge

Extensive taxi driver training of London streets, major routes and
landmarks; it takes approximately 2 years to acquire



Cohort effect

Similarities in a group due to common temporal experience or
common life experiences





Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Positive Critiques…

Specificity of Test Subjects

MARRY

Experimental:

16 right
-
handed male taxi drivers between the ages
of 32 and 62 years old, in occupation for a minimum of 18 months


Control:

50 healthy, right
-
handed male non
-
taxi drivers




Ensured to use subjects with healthy bodily and


mental profiles



Prevented most size differentials due to


sex, age, or physical illnesses from


influencing results




Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Positive Critiques…

Utilization of Two Independent Imaging
Techniques to Observe Changes in Size

MARRY

Voxel Based Morphometry (VBM) with statistical parametric
mapping:

calculated volumetric differences in brain matter of
subject MRI scans from a template control


Pixel counting:

volume calculated by adding all cross
-
sectional
areas and multiplying by the distance between adjacent MRI scans





Results from VBM could be further verified


with results from pixel counting



Further contributed to the reliability


of results




Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Critiques…

Possible Areas of Improvements

MARRY






Assessing subjects’ psyches



Non
-
taxi drivers: occupations?



Role of stress

Critiques…

Vagueness of the Term “Mental Map”

RORY



Maguire and others proposed that the larger hippocampus


size in taxi drivers was due to their “
spatial representation of


London
” or their “
mental map






There is a potential problem with the vagueness of the


term “
mental map





Other Research has suggested the


role of the hippocampus is more


specific




Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Critiques…

Side Road Memory

RORY



The hippocampus may be involved specifically with


SIDE ROAD memory




A 2006 Maguire Study of Patient TT


Patient TT:



A retired London Taxi Driver with 37 years experience



Primarily bilateral hippocampus damage due


to limbic encephalitis



Maguire, A., Nannery, R., and Spier, H. (2006). Navigation around London by a
taxi driver with bilateral hippocampal lesions.
Brain
. 129, 2894
-
2907.

Critiques…

Side Road Memory

RORY



TT retained a large amount of navigationally
-
relevant information





Normal landmark recognition, and relational and orientation


knowledge about central London






Used a video game simulation of


London to test his ability


to navigate London




‘The Getaway’

2002 Sony Computer

Entertainment Europe

Critiques…

Side Road Memory

RORY



Was able to navigate virtual London surprisingly well




However had considerable difficulty when the routes required


Non
-
A Roads




A
-
Roads are the major


arteries of London




The Orange Roads


are A
-
Roads




Maguire, A., Nannery, R., and Spier, H. (2006).
Navigation around London by a taxi driver with
bilateral hippocampal lesions.
Brain
. 129, 2894
-
2907.

Critiques…

Non A
-
Road Deficit

RORY

Clear Deficit on routes that

could be navigated without

A
-
Roads



Main Arteries of city become

semantic knowledge non
-
A

roads are episodic?

Maguire, A., Nannery, R., and Spier, H. (2006). Navigation around London by a
taxi driver with bilateral hippocampal lesions.
Brain
. 129, 2894
-
2907.

Critiques…

Landmark Memory

RORY

A Toronto study:


Possible role of hippocampus for landmark memory?


Patient SB



Taxi driver in downtown Toronto for 30 yrs and courier in


downtown Toronto for 15 yrs



Hippocampus damage due to Alzheimer's disease



Impaired memory for recently learned items




Rosenbaum, R., Gao, F.,Richards, B., Black, S., and Moscovitch, M. (2005). ‘‘Where to?’’
Remote Memory for Spatial Relations and Landmark Identity in Former Taxi Drivers with
Alzheimer’s Disease and Encephalitis.
Journal of Cognitive Neuroscience.

Critiques…

Landmark Memory

RORY



SB had intact navigational abilities based on remote


spatial memory




Was able to devise an alternate route to avoid a detour, and


Complete vector
-
mapping tests for orientation and distance




Had an understanding of where landmarks were in the city, and

How to get from one landmark to another


HOWEVER:


Could not recognize Toronto

or World Landmarks, and could not

identify them




Rosenbaum, R., Gao, F.,Richards, B., Black, S., and Moscovitch, M. (2005). ‘‘Where to?’’
Remote Memory for Spatial Relations and Landmark Identity in Former Taxi Drivers with
Alzheimer’s Disease and Encephalitis.
Journal of Cognitive Neuroscience.

Critiques…

Landmark Memory

RORY

Rosenbaum, R., Gao, F.,Richards, B., Black, S., and Moscovitch, M. (2005). ‘‘Where to?’’
Remote Memory for Spatial Relations and Landmark Identity in Former Taxi Drivers with
Alzheimer’s Disease and Encephalitis.
Journal of Cognitive Neuroscience.

RORY

Google Earth

LONDON PROPERTY GROWTH

Created by “Barnabu”

http://www.barnabu.co.uk






Timeline of the 60 tallest buildings to be created
and demolished in London over the last 50 years

Critiques…

Changing London

AMINA



Landmarks and side roads change much more rapidly than the
main arteries of a city




London has experienced rapid growth in the past few decades


Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Critiques…

Possible Explanations of Maguire’s Results

RORY

Possible Causes
:



Cohort effect?



More time as


Taxi Driver =


More changes in


London




Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Critiques…

The Knowledge

AMINA



25,000 streets




Know all points of interest, such as theatres, hospitals,


railway stations, police stations, courts, shopping


centers, etc.




Know the names and order of the side streets,


and traffic signals and regulations passed


on the route

"The Knowledge”, Public Carriage Office, Transport for London

http://www.tfl.gov.uk/businessandpartners/taxisandpri vatehi re/1412.aspx

Critiques…

Maguire’s Approach

AMINA




Instead of testing out the predisposition notion, Maguire makes
the assumption that the hippocampi of London taxi drivers were
of average size initially.




A far better approach would be include subjects just starting
their training, and subjects at month 0 on the job.




Or a longitudinal study to more accurately eliminate any
individual differences between subjects.


Maguire, E.A., et al.
(2000). Navigation
-
related structural change in the
hippocampi of taxi drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.

Follow up Studies…

London Taxi Drivers & Bus Drivers: Structural
MRI & Neuropsychological Analysis

RACHEL

Question


Gray matter differences…



Are they really a result of spatial representations over time or does
driving experience and/or stress play a role?





Maguire, E.A., Woollett, K., Spiers, H.J. (2006). London Taxi Drivers and Bus
Drivers: A Structural MRI and Neuropsychological Analysis. Hippocampus, 16,
1091
-
1101.

Follow up Studies…

London Taxi Drivers & Bus Drivers: Structural
MRI & Neuropsychological Analysis

RACHEL

Results



Bus drivers were not found to have a difference in gray matter
volume related to years of driving experience



Stress did not differ in bus drivers versus taxi drivers



Taxi drivers were found to better at naming London landmarks
and knowing their relative distances between

compared to that of London bus drivers





Maguire, E.A., Woollett, K., Spiers, H.J. (2006). London Taxi Drivers and Bus
Drivers: A Structural MRI and Neuropsychological Analysis. Hippocampus, 16,
1091
-
1101.

Follow up Studies…

London Taxi Drivers & Bus Drivers: Structural
MRI & Neuropsychological Analysis

RACHEL


Conclusions


Large amount of spatial information and the variety of destinations
and start sites requires reconfiguring of that information by taxi
drivers could be responsible for the increased volume of the
hippocampus




Maguire, E.A., Woollett, K., Spiers, H.J. (2006). London Taxi Drivers and Bus
Drivers: A Structural MRI and Neuropsychological Analysis. Hippocampus, 16,
1091
-
1101.

Follow up Studies…

Non
-
Spatial Expertise and Hippocampal Gray
Matter Volume in Humans

RACHEL


Question


Can this hippocampus volume size difference be attributed simply
to the large gaining of knowledge or was it the specifically large
amounts of spatially specific information?




Woollett, K., Glensman, J. & Maguire, E.A. (2008). Non
-
Spatial Expertise and
Hippocampal Gray Matter Volume in Humans. Hippocampus, 18, 981
-
984.

Follow up Studies…

Non
-
Spatial Expertise and Hippocampal Gray
Matter Volume in Humans

RACHEL

Results


Doctors learn a large amount of non
-
spatial information in a given
time period


Doctors were found to have
NO

correlation between number
years worked and gray matter volume


Conclusions

Differing hippocampal volumes can be seen

when the knowledge acquired is explicitly

spatial and requiring great detail and

precision retrieval


Woollett, K., Glensman, J. & Maguire, E.A. (2008). Non
-
Spatial Expertise and
Hippocampal Gray Matter Volume in Humans. Hippocampus, 18, 981
-
984.

Class Discussion…

AMINA

GPS navigation systems are becoming increasingly common and
there is recent talk in London, of fitting such systems into the taxi
cabs.



If this study was repeated 50 years from now, how might
the reliance on GPS affect results?



same size?

References

Maguire, E.A., et al. (2000). Navigation
-
related structural change in the hippocampi of taxi
drivers [see comments].
Proc Natl Acad Sci USA,
97,

4398
-
4403.


Maguire, A., Nannery, R., and Spier, H. (2006). Navigation around London by a taxi driver
with bilateral hippocampal lesions.
Brain
. 129, 2894
-
2907.


Maguire, E.A., Woollett, K., Spiers, H.J. (2006). London Taxi Drivers and Bus Drivers: A
Structural MRI and Neuropsychological Analysis. Hippocampus, 16, 1091
-
1101.


Rosenbaum, R., Gao, F.,Richards, B., Black, S., and Moscovitch, M. (2005). ‘‘Where to?’’
Remote Memory for Spatial Relations and Landmark Identity in Former Taxi Drivers with
Alzheimer’s Disease and Encephalitis.
Journal of Cognitive Neuroscience.


"The Knowledge”, Public Carriage Office, Transport for London

http://www.tfl.gov.uk/businessandpartners/taxisandprivatehire/1412.aspx


Woollett, K., Glensman, J. & Maguire, E.A. (2008). Non
-
Spatial Expertise and Hippocampal
Gray Matter Volume in Humans. Hippocampus, 18, 981
-
984.