Abstract
Successful navigation relies on the flexible and appropriate use of metric representations of space or topological knowledge of the environment. Spatial dimensions (2D vs. 3D), spatial scales (vista-scale vs. large-scale environments) and the abundance of visual landmarks critically affect navigation performance and behavior in healthy human subjects. Virtual reality (VR)-based navigation paradigms in stationary position have given insight into the major navigational strategies, namely egocentric (body-centered) and allocentric (world-centered), and the cerebral control of navigation. However, VR approaches are biased towards optic flow and visual landmark processing. This major limitation can be overcome to some extent by increasingly immersive and realistic VR set-ups (including large-screen projections, eye tracking and use of head-mounted camera systems). However, the highly immersive VR settings are difficult to apply particularly to older subjects and patients with neurological disorders because of cybersickness and difficulties with learning and conducting the tasks. Therefore, a need for the development of novel spatial tasks in real space exists, which allows a synchronous analysis of navigational behavior, strategy, visual explorations and navigation-induced brain activation patterns. This review summarizes recent findings from real space navigation studies in healthy subjects and patients with different cognitive and sensory neurological disorders. Advantages and limitations of real space navigation testing and different VR-based navigation paradigms are discussed in view of potential future applications in clinical neurology.
Highlights
In the last decades, we have gained fundamental insight into human navigation control from case studies in patients with circumscribed cerebral lesions and functional MRI studies using navigation tasks in well-controlled and distinct virtual reality (VR) settings (Maguire et al, 1998, 2000, 2003, 2006; Astur et al, 2002; Boccia et al, 2014; McCormick et al, 2017, 2018).Real-Space Navigationperforming navigation tasks in VR has obvious methodological limitations
The main difference between these two groups was an inferior performance for allocentric and egocentric route learning in amyloid positive amnestic mild cognitive impairment (aMCI) patients as compared to amyloid negative patients, who had impaired navigation abilities only on allocentric routes (Schöberl et al, 2020). aMCI patients had decreased activations in the hippocampus, retrosplenial cortex (RSC), posterior parietal cortex (PPC), TABLE 1 | Comparison of different virtual reality (VR) and real space-based navigation paradigms
The currently available VR set-ups do have considerable limitations, especially if it comes to application in older subjects and patients with sensory or cognitive disorders: (1) desktop VR has a strong bias towards optic flow and visual processing and does not resemble the multisensory inputs during naturalistic real space navigation; (2) treadmill walking in large-scale VR and highly immersive head-mounted VR systems allow for some degree of optic flow, vestibular and proprioceptive input
Summary
We have gained fundamental insight into human navigation control from case studies in patients with circumscribed cerebral lesions and functional MRI (fMRI) studies using navigation tasks in well-controlled and distinct virtual reality (VR) settings (Maguire et al, 1998, 2000, 2003, 2006; Astur et al, 2002; Boccia et al, 2014; McCormick et al, 2017, 2018). PET-based measurement of cerebral glucose metabolism while absolving a real space navigation task confirmed the prominent role of simultaneous hippocampal as well as RSC activations for human navigation, indicating that these two brain regions are the critical hubs for human navigation in naturalistic and novel environments (Zwergal et al, 2016; Irving et al, 2018b). PET measurements in the post-acute stage showed increased brain activations of the right hippocampus and bilateral RSC, posterior parietal and mesiofrontal cortex (Schöberl et al, 2019; Figure 4B) These findings can be interpreted as a compensatory upregulation of the human cerebral navigation network including the regions. The main difference between these two groups was an inferior performance for allocentric and egocentric route learning in amyloid positive aMCI patients as compared to amyloid negative patients, who had impaired navigation abilities only on allocentric routes (Schöberl et al, 2020). aMCI patients had decreased activations in the hippocampus, RSC, PPC,
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
