MAGUIRE E., FRACKOWIAK R., FRITH C. (1997) RECALLING ROUTES AROUND LONDON: ACTIVATION OF THE RIGHT HIPPOCAMPUS IN TAXI DRIVERS JOURNAL OF NEUROSCIENCE, 17,

BACKGROUND 2

WHERE IS SPATIAL MEMORY? 3 here?

POSITRON EMISSION TOMOGRAGRAPHY (PET) SCAN PET – positron emission tomography 4

MAGUIRE ET AL (1997) 5

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 6

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 7

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? 8

PROCEDURE Tasks: describe… routes (shortest legal)  T+ S+ landmarks (not in London)  T+ S- film plots (famous)  T- S+ film frames (stills)  T- S- 4-digit numbers (baseline comparison task) 9

PROCEDURE 10 T+T- S+ RoutesFilm plots S- LandmarksFilm frames

CONTROLS repeat 4-digit numbers as baseline comparison task participants blindfolded throughout speech output digitally recorded identical procedure for each participant 11

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) 12

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 13

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) 14

CONCLUSIONS o semantic topographical memory retrieval is associated with the R hippocampus o ‘entirely different’ brain regions are activated during topographc and non- topographic memory retrieval o the role of the R hippocampus (and some specific other brain regions) in processing spatial layouts over long time periods o both topographical tasks (routes and landmarks) activated many of the same brain areas o main difference: activation of R hippocampus in routes task, not in landmarks task. Route planning (=navigation) appears to be located in the R hippocampus 15

W HERE IN THE BRAIN IS THE HIPPOCAMPUS ? 16 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!!!

APPLICATION Is this research useful? Why? Why not? Does it matter? Topographical disorientation after brain lesions Humans and many animals can navigate in large- scale 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. 17

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 18

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) 19

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) 20

REVIEW Where was/were the  experimental design  IV  DV  Factors of interest  Method/procedure  Main results/findings 21