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www.NTNU.no /fMRI. Human navigation abilities elucidated using functional MRI and virtual reality. Asta K. Håberg Trondheim fMRI gruppe Department of Neuroscience Norwegian University of Science and Technology (NTNU). Navigation. Memory test (objects-places-events ++) - PowerPoint PPT Presentation
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Asta K. HåbergTrondheim fMRI gruppe
Department of NeuroscienceNorwegian University of Science and Technology (NTNU)
Human navigation abilities elucidated using
functional MRI and virtual reality
www.NTNU.no/fMRI
Navigation
- Memory test (objects-places-events ++)
- Ecologically valid
- Impaired navigation abilities present in different disorders (Alzheimer’s disease, neurodevelopmental disorders)
- Used extensively in animal research (translational potential)
Hippocampus
Posterior(Back)
Anterior(Front)
Medial temporal lobe with hippocampus
Healthy Demented
Example of VR environment
~62 m
~74 m
Movement plots
Target
Start
Navigation activates a network of cortical and subcortical regions
Xu et al., 2010
Size of the place fields along the hippocampal A-P axis
Anterior- posterior axis of hippocampus
Navigation
RESEARCH QUESTIONS:
1. Different demands during navigation period gives rise to different activity?
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
3. Are there differences between men and women?
4. What distinguishes successful and unsuccessful navigation?
Navigation
1. Different demands during navigation period gives rise to different activity?
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
3. Are there differences between men and women?
4. What distinguishes successful and unsuccessful navigation?
Landmarks removed
Unaltered environment
1. Different demands during navigation period gives rise to
different activity?
- Hippocampal activity throughout the navigation period
only found in intact environment
-Hippocampal activity highly specific for different periods
-The specific demands of the different navigational periods affect
the interaction of the hippocampus with other brain regions
Navigation
1. Different demands during navigation period gives rise to different activity?
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
3. Are there differences between men and women?
4. What distinguishes successful and unsuccessful navigation?
Functional segregation of the representation of space along hippocampus A-P axis
Spatial detail is represented by posterior hippocampus
Spatial coherence (map like overview ) is represented in
anterior hippocampus
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
Navigation
1. Different demands during navigation period gives rise to different activity?
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
3. Are there differences between men and women?
4. What distinguishes successful and unsuccessful navigation?
Success rate for reaching target, men and women
Trajectory mapping
1st target landmark
Differences in navigation strategy
Men and women moved the same distance, but:
1. Men picked shortcuts
2. Men used a map-like representation of the environment
3. Men were better at making correct judgments wrt
distance and direction between objects
Male>female
Female>male
During the entire navigation periodmen have more hippocampal activity than women
In men hippocampal activity is accompanied by
increase interaction with
orbitofrotal cortex and precuneus
3. Are there differences between men and women?
- Men and women use different navigation strategies
- The male navigation strategy is more successful
- Men use a map-like representation of space, and the
direction and distance between objects are more
correctly and precisely positioned.
- The differences in navigation behavior is reflected in
differences in hippocampal activity and hippocampal
interaction with other brain regions.
Navigation
1. Different demands during navigation period gives rise to different activity?
2. Can we find evidence for a difference along the anterior-posterior axis of the hippocampus?
3. Are there differences between men and women?
4. What distinguishes successful and unsuccessful navigation?
Anterior hippocampus Posterior hippocampus
BOLD signal time courses for successful and unsuccessful trials
Target reached
Navigational success seems particularly dependent on activation of the anterior (front) of the hippocampus
4. What distinguishes successful and unsuccessful navigation?
Conclusions
Acknowledgement
Funding: NTNU, MI lab (Norwegian Research Council), Women in
sciences grant (NTNU), Department of Radiology (St. Olav’s Hospital)
Postdoc
PhD Hanne Lehn
MD PhD Jian Xu
Medical research student
Carl WS Pintzka
PhD student
Hallvard R. Evensmoen
Thank you
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