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Knowing Where & Getting There: A Human Navigation Network

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. Outline. Enakshi. Background Purpose Experimental Methods Results & Interpretation

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Knowing Where & Getting There: A Human Navigation Network

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  1. 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

  2. Outline Enakshi • Background • Purpose • Experimental Methods • Results & Interpretation • Questions

  3. Background Enakshi • Hippocampal formation • Place cells & head direction cells in rats • Allocentric representations • Posterior parietal lobe • Egocentric representations

  4. Purpose Enakshi • To investigate the neural basis of navigation in humans by studying the role of the hippocampus in human navigation

  5. Experimental Methods Enakshi • 10 subjects • Familiarized to virtual reality town • Internal representation Fig 1A

  6. Experimental Methods Enakshi • Nav1: • subjects move directly toward the destination • Nav2: • subjects must take detour to get to the destination

  7. Virtual Reality Town Enakshi • Nav1 - yellow • direct route • A - B • Nav2 - green • detour • A – B • lost – red • A – no mans land Fig 2A

  8. Experimental Methods Enakshi • Arrow-task: • subjects follow a trail of arrows to destination • Static-scenes: • subjects identify static scenes from town

  9. Experimental Methods Enakshi • Positron Emission Tomography (PET) • to visualize activated areas in the brain

  10. Experimental Methods Enakshi • 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

  11. Quantitative Results Safiah • Nav1 (direct) • 22/30 successes • Nav2 (detour) • 21/30 successes

  12. Neuroimaging Results Safiah • Successful trials • Right hippocampus • Unsuccessful trials • Left hippocampus • Left frontal and lateral temporal cortex • Thalamus

  13. Results and Interpretation 1 Safiah • Imaging of successful trials Fig 1B

  14. Results and Interpretation 2 Safiah ACCURACY OF DIRECTION Fig 2B,C

  15. Results and Interpretation 2 Safiah • Right Hippocampus • Allocentric representation of space • Start to destination • Right Inferior Parietal Cortex • Egocentric aspects of movement • Enables movement around objects toward goal

  16. Results and Interpretation 3 Safiah • NAV2 VS NAV1: LEFT MIDDLE AND SUPERIOR FRONTAL GYRI AND RIGHT CEREBELLUM Fig 3A

  17. Results and Interpretation 3 Safiah • Left Middle and Superior Frontal Gyri • Planning and decision making

  18. Results and Interpretation 4 Safiah • SUBTRACTING STATIC CONDITION: RIGHT INFERIOR PARIETAL CORTEX + BILATERAL MEDIAL TEMPORAL CORTEX Fig 3B

  19. Results and Interpretation 5 Safiah SPEED OF NAVIGATION: RIGHT CAUDATE NUCLEUS Right caudate nucleus Fig3D Fig3C

  20. Summary of Results Safiah Active areas: Successful trials vs. Arrow-task and Unsuccessful trials

  21. Summary of Results Safiah rCBF shown activity during nav1 and nav2

  22. 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

  23. Main Conclusions Parietal role in monkeys Humans vs. Rats Hippocampus Enakshi

  24. 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.

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