Travel in the Physical and Mental Space: A Behavioral Assessment of the Phylogenetic Continuity Hypothesis Between Egocentric Navigation and Episodic Memory

Based on the neuro-functional association between navigation in the physical and the mental space at the level of the hippocampal-entorhinal system, Buzsáki and Moser (2013) have hypothesized a phylogenetic continuity between spatial navigation and declarative memory functions. According to this proposal, mechanisms of episodic and semantic memory would have evolved from mechanisms of self-based and map-based navigation in the physical space, respectively. Using classic versions of path integration and item recognition tasks in human subjects, we have recently described a correlation and a predictive relationship between abilities in egocentric navigation and episodic memory. Here we aim at confirming and extending this association to the dynamic component of sequential updating in the physical (egocentric navigation) and mental (episodic memory) space, and at investigating the relationship of these self-centered abilities with semantic memory. To this aim, we developed three new experimental tasks in which the dynamic component of updating information is particularly emphasized in the spatial, the temporal, and the semantic domain. The contribution of visual short-term memory to the three tasks was also controlled by including an additional task. The results confirmed the existence of a direct and predictive relationship between self-based spatial navigation and episodic memory. We also found a significant association between egocentric navigation and semantic memory, but this relationship was explained by short-term memory abilities and was mediated by episodic memory functions. Our results support the hypothesis of an evolutionary link between mechanisms that allow spatial navigation in the physical space and time travel in the mental space.

Vestibular rehabilitation using a virtual environment for driver safety

Driving is a necessity of life, and it requires multi-sensory input and processing. Often vestibular impaired patients suffer from dysfunctional sensory input that impairs their driving. Therefore, driver's attention, and egocentric navigation skills are investigated in this project through the use of a spaceball driving simulator. This thesis clarly demonstrates and specifies the steps of implementation of a driving simulator into the spaceball. Driver attention was tested through the use of computer and audio reflex time and was used to analyze the improvement in reaction time. Seat perturbation reflex time test was used to analyze the driver egomotion awareness on the simulator. The experimental results illustrate the improvement in the driving rehabilitation field of reaction time which leads to the conclusion that the visual-proprioceptive virtual driving simulator could provide treatment to the vestibular impaired patients.

Vestibular rehabilitation using a virtual environment for driver safety

Driving is a necessity of life, and it requires multi-sensory input and processing. Often vestibular impaired patients suffer from dysfunctional sensory input that impairs their driving. Therefore, driver's attention, and egocentric navigation skills are investigated in this project through the use of a spaceball driving simulator. This thesis clarly demonstrates and specifies the steps of implementation of a driving simulator into the spaceball. Driver attention was tested through the use of computer and audio reflex time and was used to analyze the improvement in reaction time. Seat perturbation reflex time test was used to analyze the driver egomotion awareness on the simulator. The experimental results illustrate the improvement in the driving rehabilitation field of reaction time which leads to the conclusion that the visual-proprioceptive virtual driving simulator could provide treatment to the vestibular impaired patients.

The Combined Effect of APOE and BDNF Val66Met Polymorphisms on Spatial Navigation in Older Adults

Background: The apolipoprotein E (APOE) ɛ4 allele is associated with episodic memory and spatial navigation deficits. The brain-derived neurotrophic factor (BDNF) Met allele may further worsen memory impairment in APOE ɛ4 carriers but its role in APOE ɛ4-related spatial navigation deficits has not been established. Objective: We examined influence of APOE and BDNF Val66Met polymorphism combination on spatial navigation and volumes of selected navigation-related brain regions in cognitively unimpaired (CU) older adults and those with amnestic mild cognitive impairment (aMCI). Methods: 187 participants (aMCI [n = 116] and CU [n = 71]) from the Czech Brain Aging Study were stratified based on APOE and BDNF Val66Met polymorphisms into four groups: ɛ4–/BDNFVal/Val, ɛ4–/BDNFMet, ɛ4+/BDNFVal/Val, and ɛ4+/BDNFMet. The participants underwent comprehensive neuropsychological examination, brain MRI, and spatial navigation testing of egocentric, allocentric, and allocentric delayed navigation in a real-space human analogue of the Morris water maze. Results: Among the aMCI participants, the ɛ4+/BDNFMet group had the least accurate egocentric navigation performance (p < 0.05) and lower verbal memory performance than the ɛ4–/BDNFVal/Val group (p = 0.007). The ɛ4+/BDNFMet group had smaller hippocampal and entorhinal cortical volumes than the ɛ4–/BDNFVal/Val (p≤0.019) and ɛ4–/BDNFMet (p≤0.020) groups. Among the CU participants, the ɛ4+/BDNFMet group had less accurate allocentric and allocentric delayed navigation performance than the ɛ4–/BDNFVal/Val group (p < 0.05). Conclusion: The combination of APOE ɛ4 and BDNF Met polymorphisms is associated with more pronounced egocentric navigation impairment and atrophy of the medial temporal lobe regions in individuals with aMCI and less accurate allocentric navigation in CU older adults.

Egocentric Navigation Abilities Predict Episodic Memory Performance

The medial temporal lobe supports both navigation and declarative memory. On this basis, a theory of phylogenetic continuity has been proposed according to which episodic and semantic memories have evolved from egocentric (e.g., path integration) and allocentric (e.g., map-based) navigation in the physical world, respectively. Here, we explored the behavioral significance of this neurophysiological model by investigating the relationship between the performance of healthy individuals on a path integration and an episodic memory task. We investigated the path integration performance through a proprioceptive Triangle Completion Task and assessed episodic memory through a picture recognition task. We evaluated the specificity of the association between performance in these two tasks by including in the study design a verbal semantic memory task. We also controlled for the effect of attention and working memory and tested the robustness of the results by including alternative versions of the path integration and semantic memory tasks. We found a significant positive correlation between the performance on the path integration the episodic, but not semantic, memory tasks. This pattern of correlation was not explained by general cognitive abilities and persisted also when considering a visual path integration task and a non-verbal semantic memory task. Importantly, a cross-validation analysis showed that participants' egocentric navigation abilities reliably predicted episodic memory performance. Altogether, our findings support the hypothesis of a phylogenetic continuity between egocentric navigation and episodic memory and pave the way for future research on the potential causal role of egocentric navigation on multiple forms of episodic memory.

Learning a Path from Real Navigation: The Advantage of Initial View, Cardinal North and Visuo-Spatial Ability

Background: Spatial cognition research strives to maximize conditions favoring environment representation. This study examined how initial (egocentric) navigation headings interact with allocentric references in terms of world-based information (such as cardinal points) in forming environment representations. The role of individual visuo-spatial factors was also examined. Method: Ninety-one undergraduates took an unfamiliar path in two learning conditions, 46 walked from cardinal south to north (SN learning), and 45 walked from cardinal north to south (NS learning). Path recall was tested with SN and NS pointing tasks. Perspective-taking ability and self-reported sense of direction were also assessed. Results: Linear models showed a better performance for SN learning and SN pointing than for NS learning and NS pointing. The learning condition x pointing interaction proved SN pointing more accurate than NS pointing after SN learning, while SN and NS pointing accuracy was similar after NS learning. Perspective-taking ability supported pointing accuracy. Conclusions: These results indicate that initial heading aligned with cardinal north prompt a north-oriented representation. No clear orientation of the representation emerges when the initial heading is aligned with cardinal south. Environment representations are supported by individual perspective-taking ability. These findings offer new insight on the environmental and individual factors facilitating environment representations acquired from navigation.

A neural code for egocentric spatial maps in the human medial temporal lobe

SummarySpatial navigation relies on neural systems that encode information about places, distances, and directions in relation to the external world or relative to the navigating organism. Since the proposal of cognitive maps, the neuroscience of navigation has focused on allocentric (world-referenced) neural representations including place, grid, and head-direction cells. Here, using single-neuron recordings during virtual navigation, we identify “anchor cells” in the human brain as a neural code for egocentric (self-centered) spatial maps: Anchor cells represent egocentric directions towards “anchor points” located in the environmental center or periphery. Anchor cells were abundant in parahippocampal cortex, supported full vectorial representations of egocentric space, and were integrated into a neural memory network. Neurons encoding allocentric direction complemented anchor-cell activity, potentially assisting anchor cells in transforming percepts into allocentric representations. Anchor cells may facilitate egocentric navigation strategies, may support route planning from egocentric viewpoints, and may underlie the first-person perspective in episodic memories.