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