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

OutlineEnakshi

Background

Hippocampal formation

Place cells & head direction cells in rats

Allocentric representations

Posterior parietal lobe

Egocentric representations

Enakshi

Purpose

To investigate the neural basis of navigation in humans by studying the role of the hippocampus in human navigation

Enakshi

Experimental Methods

10 subjects Familiarized to virtual reality town

Internal representation

Fig 1A

Enakshi

Experimental Methods

Nav1:

subjects move directly toward the destination

Nav2:

subjects must take detour to get to the destination

Enakshi

Virtual Reality Town

Fig 2A

Nav1 - yellow direct route A - B

Nav2 - green detour A – B

lost – red A – no mans land

Enakshi

Experimental Methods

Arrow-task:

subjects follow a trail of arrows to destination

Static-scenes:

subjects identify static scenes from town

Enakshi

Experimental Methods

Positron Emission Tomography (PET) to visualize activated areas in the

brain

Enakshi

Experimental Methods

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

Enakshi

Quantitative Results

Nav1 (direct)

22/30 successes

Nav2 (detour)

21/30 successes

Safiah

Neuroimaging Results

Successful trials

Right hippocampus

Unsuccessful trials

Left hippocampus

Left frontal and lateral temporal cortex

Thalamus

Safiah

Results and Interpretation 1

Imaging of successful trials

Fig 1B

Safiah

Results and Interpretation 2

Fig 2B,C

Safiah

ACCURACY OF DIRECTION

Results and Interpretation 2 Right Hippocampus

Allocentric representation of space

Start to destination

Right Inferior Parietal Cortex Egocentric aspects of movement

Enables movement around objects toward goal

Safiah

Results and Interpretation 3

Fig 3A

Safiah

NAV2 VS NAV1: LEFT MIDDLE AND SUPERIOR FRONTAL GYRI AND RIGHT CEREBELLUM

Results and Interpretation 3

Left Middle and Superior Frontal Gyri

Planning and decision making

Safiah

Results and Interpretation 4

Fig 3B

Safiah

SUBTRACTING STATIC CONDITION: RIGHT INFERIOR PARIETAL CORTEX + BILATERAL MEDIAL TEMPORAL CORTEX

Results and Interpretation 5

Fig 3D Fig 3C

Right caudate nucleus

Safiah

SPEED OF NAVIGATION: RIGHT CAUDATE NUCLEUS

Summary of Results

Active Areas during successful trials

Arrow task - R. hippocampus

Unsuccessful

- L. hippocampus

- L. lateral temporal cortex

- L. frontal cortex

- thalamus

Active areas:

Successful trials vs. Arrow-task and Unsuccessful trials

Safiah

Summary of Results

nav1 nav 2

Shown activity

- R. Hippocampus- R. inferior parietal cortex

- L. Frontal activation

Speed of navigation

- R. Caudate nucleus

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rCBF shown activity during nav1 and nav2

Safiah

Main Conclusions

Results agree with previous findings: lesions in right hippocampus spatial

memory defects

rCBF in R. caudate nucleus is correlated with navigation speed

motor learning and context recognition

Enakshi

Main Conclusions

Parietal role in monkeys

Humans vs. Rats Hippocampus

Enakshi

References 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.