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Erschienen in:
02.08.2018 | Original Communication
A novel real-space navigation paradigm reveals age- and gender-dependent changes of navigational strategies and hippocampal activation
Erschienen in: Journal of Neurology | Sonderheft 1/2018
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Objective
To establish a novel multimodal real-space navigation paradigm and define age- and gender-related normative values for navigation performance and visual exploration strategies in space.
Methods
A group of 30 healthy subjects (mean age 45.9 ± 16.5 years, 16 men) performed a real-space navigation paradigm, requiring allo- and egocentric spatial orientation abilities. Visual exploration behaviour and navigation strategy were documented by a gaze-controlled, head-fixed camera. Allo- and egocentric spatial orientation performance were compared in younger and older subjects (age threshold 50 years) as well as men and women. Navigation-induced changes of regional cerebral glucose metabolism (rCGM) were measured by [18F]-fluorodeoxyglucose-positron emission tomography in a subgroup of 15 subjects (8 men) and compared across age and gender.
Results
The majority of healthy subjects (73.3%) completed the navigation task without errors. There was no gender difference in navigation performance. Normalized total error rates increased slightly, but significantly with age (r = 0.36, p = 0.05). Analysis of navigation path indicated a significantly reduced use of short cuts in older age (r = 0.44, p = 0.015). Visual exploration analysis revealed that older subjects made significantly more total saccades (r = 0.49, p = 0.006) and search saccades (r = 0.54, p = 0.002) during navigation. All visual exploration parameters were similar in men and women. Navigation-induced rCGM decreased with age in the hippocampus and precuneus and increased in the frontal cortex, basal ganglia and cerebellum. Women showed an increase of rCGM in the left hippocampus and right middle temporal gyrus, men in the superior vermis.
Conclusion
Real-space navigation testing was a feasible and sensitive method to depict age-related changes in navigation performance and strategy. Normalized error rates, total mean durations per item and total number of saccades were the most sensitive and practical parameters to indicate deterioration of allocentric navigation strategies and right hippocampal function in age irrespective of gender.