MAGUIRE E., FRACKOWIAK R., FRITH C. (1997)
RECALLING ROUTES AROUND
L O N D O N : A C T I VAT I O N O F T H E
R I G H T H I P P O C A M P U S I N TA X I
DRIVERS
JOURNAL OF NEUROSCIENCE,
17, 7103-7110
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WHERE IS SPATIAL MEMORY?
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POSITRON EMISSION TOMOGRAGRAPHY (PET) SCAN
PET – positron emission tomography
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MAGUIRE ET AL (1997)
Aim:
Investigate the neural basis for spatial memory
Method:
Using PET, measure neural activity during
topographical (=space/location) semantic
(=facts/language) memory tasks
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MAGUIRE ET AL (1997)
Participants:
11London black-cab taxi drivers
Average age 45
Average experience 14.5 years
Informed written consent
Local hospital ethics committee approved the study
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PROCEDURE
Factorial design, 2 factors of interest:
Topographical and sequencing memory
Why? To distinguish brain activity during route planning, i.e. places in order (topo. & seq.),
from brain activity during other types of memory task
How?
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PROCEDURE
Tasks: describe…
routes (shortest legal)  T+ S+
landmarks (not in London)  T+ Sfilm plots (famous)  T- S+
film frames (stills)  T- S-
4-digit numbers (baseline comparison task)
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PROCEDURE
T+
S+
S-
T-
Routes
Film plots
Landmarks
Film
frames
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CONTROLS
repeat 4-digit numbers as baseline comparison task
participants blindfolded throughout
speech output digitally recorded
identical procedure for each participant
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PET SCANS
Data is gathered over 90 seconds following the radioactive injection
During each scan one item is presented (i.e. one route / plot / landmark / frame)
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RESULTS
Comparing the two factors…
 memory type:
topographical vs. non-topographical
 sequencing: with vs. without
…with the baseline condition…
 number repetition
…gives a picture of the neural systems supporting each task
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RESULTS
Simple main effects
Routes recall:
 increased activation of the medial parietal lobe, posterior cingulate cortex, parahippocampal gyrus and the R
hippocampus
Landmarks recall:
 increased activation of the medial parietal lobe, posterior cingulate cortex, parahippocampal gyrus,
oocipitotemporal regions but not the R hippocampus
Film plots vs. frames, no sig. diff. in rCBF
 (=Regional cerebral blood flow)
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CONCLUSIONS
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semantic topographical memory retrieval is associated with the R hippocampus
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‘entirely different’ brain regions are activated during topographc and nontopographic memory retrieval
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the role of the R hippocampus (and some specific other brain regions) in
processing spatial layouts over long time periods
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both topographical tasks (routes and landmarks) activated many of the same
brain areas
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main difference: activation of R hippocampus in routes task, not in landmarks
task. Route planning (=navigation) appears to be located in the R hippocampus
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WHERE IN THE BRAIN IS THE HIPPOCAMPUS?
The hippocampus is
located in the mid
temporal lobe
The role of the
hippocampus is to
facilitate spatial
memory (navigation)
Each hemisphere of
the brain has a
hippocampus
Hippocampus means
seahorse and that’s
what its named after!!!
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APPLICATION
Is this research useful?
Why? Why not? Does it matter?
Topographical disorientation after brain lesions
Humans and many animals can navigate in largescale space. Many species with far smaller brains
can navigate successfully.
Navigation is a phylogenically old ability – located in
the ‘primitive’ hippocampus, not in frontal cerebral
regions.
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EVALUATION
Small sample?
No research on woman
… but brain scans are a relatively new research technique – each new study adds to our body
of knowledge
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ANALYSIS
Nature
Are  London taxi drivers born with unusual brains?
Nurture
Do  London taxi drivers develop unusual brains? (see Maguire et al 2000, in Banyard p158)
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CAN YOU EVALUATE THIS STUDY?
in terms of…
experimental validity (control of variables)
ecological validity (realistic task)
external validity (generalisation)
ethical validity
reliability (replication, objectivity)
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REVIEW
Where was/were the
 experimental design
 IV
 DV
 Factors of interest
 Method/procedure
 Main results/findings
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