Transcript 3FA3M5-P-B8-Knowing Where & Getting There`B8

Knowing Where & Getting There:
A Human Navigation Network
Eleanor A. Maguire et al.
Group B8: Enakshi Singh, Meinas Elmusharaf, Adam
Ouellette, Seung Na & Safiah Mai
To be presented by: Enakshi & Safiah
Enakshi
Outline
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Background
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Purpose
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Experimental Methods
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Results & Interpretation
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Questions
Enakshi
Background
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Hippocampal formation
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Place cells & head direction cells in rats
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Allocentric representations
Posterior parietal lobe
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Egocentric representations
Enakshi
Purpose
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To investigate the neural basis of navigation
in humans by studying the role of the
hippocampus in human navigation
Enakshi
Experimental Methods
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10 subjects
Familiarized to virtual reality town
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Internal representation
Fig 1A
Enakshi
Experimental Methods
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Nav1:
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subjects move directly toward the
destination
Nav2:
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subjects must take detour to get to the
destination
Enakshi
Virtual Reality Town
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Nav1 - yellow
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Nav2 - green
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direct route
A-B
detour
A–B
lost – red
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A – no mans land
Fig 2A
Enakshi
Experimental Methods
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Arrow-task:
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subjects follow a trail of arrows to
destination
Static-scenes:
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subjects identify static scenes from town
Enakshi
Experimental Methods
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Positron Emission Tomography (PET)
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to visualize activated areas in the brain
Enakshi
Experimental Methods
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Investigate which brain regions were
involved in successful navigation in both
nav1 and nav2
Explore relationship between regional
cerebral blood flow (rCBF) and
behaviour during nav1
Safiah
Quantitative Results
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Nav1 (direct)
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22/30 successes
Nav2 (detour)
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21/30 successes
Safiah
Neuroimaging Results
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Successful trials
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Right hippocampus
Unsuccessful trials
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Left hippocampus
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Left frontal and lateral temporal cortex
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Thalamus
Safiah
Results and Interpretation 1
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Imaging of
successful trials
Fig 1B
Safiah
Results and Interpretation 2
ACCURACY OF DIRECTION
Fig 2B,C
Safiah
Results and Interpretation 2
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Right Hippocampus
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Allocentric representation of space
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Start to destination
Right Inferior Parietal Cortex
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Egocentric aspects of movement
Enables movement around objects toward
goal
Safiah
Results and Interpretation 3
NAV2 VS NAV1: LEFT MIDDLE AND SUPERIOR
FRONTAL GYRI AND RIGHT CEREBELLUM
Fig 3A
Safiah
Results and Interpretation 3
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Left Middle and Superior Frontal Gyri
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Planning and decision making
Safiah
Results and Interpretation 4
SUBTRACTING STATIC CONDITION: RIGHT INFERIOR PARIETAL CORTEX +
BILATERAL MEDIAL TEMPORAL CORTEX
Fig 3B
Safiah
Results and Interpretation 5
SPEED OF NAVIGATION: RIGHTRight
CAUDATE
NUCLEUS
caudate
nucleus
Fig 3C
Fig 3D
Summary of Results
Safiah
Active areas:
Successful trials vs. Arrow-task and Unsuccessful trials
Active Areas during
successful trials
Arrow task
- R. hippocampus
Unsuccessful
- L. hippocampus
- L. lateral temporal cortex
- L. frontal cortex
- thalamus
Safiah
Summary of Results
rCBF shown activity during nav1 and nav2
nav1
nav 2
Shown
activity
- R. Hippocampus
- L. Frontal
- R. inferior parietal activation
cortex
Speed of
navigation
- R. Caudate
nucleus
---
Enakshi
Main Conclusions
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Results agree with previous findings:
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lesions in right hippocampus  spatial
memory defects
rCBF in R. caudate nucleus is correlated with
navigation speed
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motor learning and context recognition
Enakshi
Main Conclusions
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Parietal role in monkeys
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Humans vs. Rats Hippocampus
References
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Maguire, E.A., Burgess, N.M., Donnett, J.G.,
Frackowiak, R.S., Frith, C.D., & O’Keefe, J. (1998).
Knowing where and getting there: a human
navigation network. Science, 280, 921-924.
Wiener, S.I. (1993). Neurobiological Learning
Memory. Journal of Neuroscience, 13, 3802.
Kinsbourne, M., Wood, F. (1975). Short-Term
Memory. Science, 257-291.