KNOWING WHERE AND GETTING THERE: A HUMAN NAVIGATION NETWORK

MAGUIRE, E.A., BURGESS, N., DONNETT, J.G., FRACKOWIAK, R.S., FRITH, C.D.  AND O'KEEFE, J. 

A Commentary Presented By:Molly O’Brien, Nicole Neil, Mudra Bhatt, Richa Sharma and James Guse

Presentation Format Introduction Critique:

Subject Selection Methodologies Experimental Validity Hippocampal Lateralization

Contextual Elements Conclusion

James Guse

The effect of age and gender on neural substrates involved in spatial navigation

Subject Selection

Richa Sharma

Age Differences in age of subjects is very

important Effects of aging on the hippocampus Direct effect on navigation

In the study, average age given and a 60 minute training session

Different age groups = Different training requirements

Richa Sharma

Gender Women

Egocentric Landmarks Right parietal and prefrontal area

Men Allocentric Geometric cues, topographic

constellation Parahippocampal and right hippocampus

Bilateral advantage hypothesis

Richa Sharma

Methodologies

James Guse

Duke Nukem 3D! ... ? Simulation of a 3D

environment A 2D maze

projected into 3D

Shading and textural details deep enough to convince participants.

James Guse

PET Scanning How do the Pixels

become Voxels? Regional Blood Flow Half Life of (15)O Effects on the

perception of space?

James Guse

Resolution Two dimensions integrated into three. 'Resolving' power maintained by replication MRI resolution: 2mmx1mmx1mm – but it's been

smoothed Losing noise always looses data. Statistical Parametric Mapping no longer just the average number of events in one voxel.

Given the averages overlain on averages, we can't say just where one cause of blood use ends and another begins.

Problems with the space – these voxels just won't fit!Overall good enough for the gross anatomical

James Guse

Experimental Validity

Nicole Neil

Virtual Environments

High ecological validity

High experimental control

Functional imaging possible during acquisition of spatial memories

Smaller field of view

Fixed distance from screen

Participants stationary

Pros Cons

Nicole Neil

Ecological Validity Primate Comparisons:

Single cell recordings from hippocampus of monkeys

Monkeys either: REAL: Navigate a cab using a joystick to receive a

reward VIRTUAL: Move a pointer on an LCD screen to receive

a reward

Similar patterns of activation across both situations

Significantly more neurons fired in the real task as opposed to the virtual task

(Matsmura, Nishijo, Tamura, Eifuku, Endo, & Ono, 1999)

Nicole Neil

1 2

3 4

Virtual Environments

High ecological validity

High experimental control

Functional imaging possible during acquisition of spatial memories

Smaller field of view

Fixed distance from screen

Participants stationary

Pros Cons

Nicole Neil

Participants Stationary

Vestibular Contributions to Spatial Memory: Participants asked to imagine/move on one leg of a

path, then turn, and imagine/move on a second leg of a turn

(Klatzky, Loomis, Beall, Chance, & Golledge, 1998)

Nicole Neil

Participants Stationary

Vestibular Contributions to Spatial Memory: Real world condition, participants either:

1) Heard description and imagined

2) Viewed experimenter walk the path

3) Walked it blindfolded

Virtual condition, participants either1) Optic flow for leg (1) presented, experimenter turned participant,

optic flow for leg (2) presented

2) Optic flow presented for both legs and turn

(Klatzky, Loomis, Beall, Chance, & Golledge, 1998)

Nicole Neil

Participants Stationary

Vestibular Contributions to Spatial Memory: Participants who made a physical turn made fewer

errors in reorienting Vestibular information important for updating spatial

system

(Klatzky, Loomis, Beall, Chance, & Golledge, 1998)

Nicole Neil

Hippocampal Lateralization

Mudra Bhatt

Right vs Left Hippocampus

Accuracy of navigation

Non-spatial navigation

Right Hippocampus Left Hippocampus

Mudra Bhatt

Right Hippocampus Activity correlates with the amount of

accurate navigation Relationship between accurate

navigation and the amount of blood flow in right hippocampus

Right hippocampus contains a vector that points toward the goal location

O’Keefe, J., Burgess, N., Donnett, J., Jeffery, K. & Maguire, E. (1998) Place cells, navigational accuracy, and the human hippocampus. Philosophical Transactions: Biological Sciences, 353 (1373), 1333-1340.

Mudra Bhatt

Left Hippocampus Left anterior hippocampus activity correlates

with spatial binding and goal-directed navigation. mediates specific component of spatial navigation

Binding an object to its spatial location

Left posterior hippocampus activity correlates navigation performance

Cornwell, B., Johnson, L., Holroyd, T., Carver, F, and Grillon, C. (2008) Human Hippocampal and Parahippocampal Theta during Goal –Directed Spatial Navigation Predicts Performance on a Virtual Morris Water Maze. The Journal of Neuroscience, 28(23), 5983-5990.

Mudra Bhatt

The role of the hippocampus in spatial navigation:

- What did Maguire et al have to build upon?- What are some of the major viewpoints?- Where does the study by Maguire et al fit in?- Where is the field headed?

Contextual Elements

Molly O’Brien

O’Keefe and Nadel, 1978

The Hippocampus as a Cognitive Map Role of the hippocampus in the:

a) Psychological representation of spacei. Animals with hippocampal damage in navigation tasksii. Recordings from hippocampal cells in freely moving rats

b) Context dependent memoryi. Amnesic memory system dissociations

O’Keefe, J. and Nadel, L., 1978. The Hippocampus as a Cognitive Map, Clarendon Press, Oxford.

Molly O’Brien

Two Distinct Camps Emerge ...

Hippocampus acts as spatial mapping system

Organize and remember items and events of experience

Hippocampus is a more general learning system

Spatial representations naturally result, but are not essential part

Cognitive Map View Relational Learning View

Knierim, J.J. (2003). Hippocampus and memory: can we have our place and fear it too? Neuron, 37 (3), 372-374.

Molly O’Brien

Where does our study fit in? Maguire et al showed that ...

“Not only is the right hippocampus more active during navigation than trail-following ...” Navigation requires cognitive map

“... but the more accurate the navigation, the more active it is.”

Recalling specific destinations and successful pathways Episodic memory function

Retrieved from: http://www.cartoonstock.com/lowres/hsc4567l.jpg

Molly O’Brien

So, which theory?

Subjects generate an overall cognitive map of the city

Map facilitates the memory of landmarks and routes in relation to one another

Subjects remember the landmarks and routes

Spatial relationships are a natural result of this memory

Cognitive Map View Relational Learning View

Molly O’Brien

Where Now? Molly O’Brien

Future Directions

Knierim (2003) suggests a more “systems-oriented” approach Develop a greater wealth of

knowledge regarding:1. Information flow between

hippocampus and surrounding areas

2. Input/output functions3. Characterize computations

performed by each

Knierim, J.J. (2003). Hippocampus and memory: can we have our place and fear it too? Neuron, 37 (3), 372-374.

Molly O’Brien

Main points from the commentary presentation

Conclusions

Take Home Points!

In vivo analysis High ecological validity Relevance to previous

research, and provides base of support for future directions

Age and gender effects on neural activation during navigation

Actual data resolution fuzzy

Participants stationary during tasks

Role of left hippocampus in spatial navigation

PROS CONS

References George Gron, A. P. (2000). Brain activation during human navigation: gender-

different neural networks as substrate of performance. Nature Neuroscience , Vol. 3(4), pp.404-408.

Giusepp Iara, L. P. (2008). Age differences in the formation and use of cognitive maps. Behavioural Brain Research .

Klatzky, R.L., Loomis, J.M., Beall, A.C., Chance, S.S., & Golledge, R.G. (1998). Spatial updating of self-position and orientation during real, imagined, and virtual locomotion. Psychological science, 9(4),293-298.

Knierim, J. J. (2003). Hippocampus and Memory Can We Have Our Place and Fear It Too? Neuron , Vol.37(3), pp.372-374.

Matsmura, N., Nishijo, H., Tamura, R., Eifuku, S., Endo, S., & Ono, T. (1999). Spatial- and Task-dependent neuronal responses during real and virtual translocation in the monkey hippocampal formation. The Journal of Neuroscience, 19(6), 2381-2393

Nadel, J. O. (1978). The Hippocampus as a Cognitive Map. Ruben C. Gur, D. A. (2000). An fMRI study of Sex Differences in Regional

Activation to a Verbal and Spatial Task. Brain and Language , Vol. 74, pp.157-170.