Spatial Navigation and Visuospatial Strategies in Typical and Atypical Aging

Age-related spatial navigation decline is more pronounced in patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) dementia. We used a realistic-looking virtual navigation test suite to analyze different aspects of visuospatial processing in typical and atypical aging. A total of 219 older adults were recruited from the Czech Brain Aging Study cohort. Cognitively normal older adults (CN; n = 78), patients with amnestic MCI (n = 75), and those with mild AD dementia (n = 66) underwent three navigational tasks, cognitive assessment, and brain MRI. Route learning and wayfinding/perspective-taking tasks distinguished the groups as performance and learning declined and specific visuospatial strategies were less utilized with increasing cognitive impairment. Increased perspective shift and utilization of non-specific strategies were associated with worse task performance across the groups. Primacy and recency effects were observed across the groups in the route learning and the wayfinding/perspective-taking task, respectively. In addition, a primacy effect was present in the wayfinding/perspective-taking task in the CN older adults. More effective spatial navigation was associated with better memory and executive functions. The results demonstrate that a realistic and ecologically valid spatial navigation test suite can reveal different aspects of visuospatial processing in typical and atypical aging.

The Impact of Neonatal Methamphetamine on Spatial Learning and Memory in Adult Female Rats

The present study was aimed at evaluating cognitive changes following neonatal methamphetamine exposure in combination with repeated treatment in adulthood of female Wistar rats. Pregnant dams and their pups were used in this study. One half of the offspring were treated indirectly via the breast milk of injected mothers, and the other half of pups were treated directly by methamphetamine injection. In the group with indirect exposure, mothers received methamphetamine (5 mg/ml/kg) or saline (1 ml/kg) between postnatal days (PD) 1–11. In the group with direct exposure, none of the mothers were treated. Instead, progeny were either: (1) treated with injected methamphetamine (5 mg/ml/kg); or (2) served as controls and received sham injections (no saline, just a needle stick) on PD 1–11. Learning ability and memory consolidation were tested on PD 70–90 in the Morris Water Maze (MWM) using three tests: Place Navigation Test, Probe Test, and Memory Recall Test. Adult female progeny were injected daily, after completion of the last trial of MWM tests, with saline or methamphetamine (1 mg/ml/kg). The effects of indirect/direct neonatal methamphetamine exposure combined with acute adult methamphetamine treatment on cognitive functions in female rats were compared. Statistical analyses showed that neonatal drug exposure worsened spatial learning and the ability to remember the position of a hidden platform. The study also demonstrated that direct methamphetamine exposure has a more significant impact on learning and memory than indirect exposure. The acute dose of the drug did not produce any changes in cognitive ability. Analyses of search strategies (thigmotaxis, scanning) used by females during the Place Navigation Test and Memory Recall Test confirmed all these results. Results from the present study suggested extensive deficits in learning skills and memory of female rats that may be linked to the negative impact of neonatal methamphetamine exposure.

A Fault-Tolerant Level Damping Algorithm for Marine INS

When the measurement error of the external reference velocity changes dramatically, the traditional level damping for marine INS needs to cut off the damping to maintain the navigation accuracy. The level channel has a large overshoot oscillation during the variable damping instantaneous, which results in obvious position deviation. In order to solve this practical problem, a damping model is established outside the INS. The most obvious advantage of the algorithm is that the damping algorithm does not affect the inertial navigation solution. The fault-tolerant algorithm realizes the automatic damping switch according to the external reference velocity error variation criterion, which avoids the velocity oscillation and position deviation. Compared with traditional methods, the algorithm presented in this paper has higher reliability and better environmental adaptability. The effectiveness of the algorithm is verified by the actual navigation test data.

NON-INTRUSIVE, VISUAL-LESS WEARABLE HAPTIC STIMULI NAVIGATIONAL ASSISTANCE FOR ELDERLY WITH DEMENTIA

Age is typically affiliated with the decline of cognitive function and the probability to be diagnosed with neurodegenerative disease, namely dementia. Of all dementia-related deficits, the paper highlights on the decline of wayfinding ability, since it is interrelated with mobility, autonomy, caregiving burden and eventually institutionalization. The sense of directions in elderly is also affected by the sensory changes, while the most obvious sensory declines are both vision and hearing. Hence navigation systems that support mainly on visual and auditory may not be the best option for them. A concept of wearable navigational assistance that is non-intrusive and uses haptic stimuli instead of visual and/or audio signals is presented in this paper. A Usability Test (UT) was performed towards the elderly with dementia at a selected nursing home to investigate how they perceive haptic-feedback as a modality of navigation. The assessments involved three phases: (1) orientation or training, (2) navigation test and (3) further navigation test. Results indicate the potential efficacy of haptic modality as a navigation signal. Improvement on subjects’ navigational performance was shown especially during the further navigation test, signifying the familiarization of the intervention. Employing the haptic modality could be a beneficial substitute for navigational purpose when vision and audio are less appropriate. Nevertheless, as much as the encouraging outcomes from the results and analysis of the assessments are valuable, the constructive reviews attained are indeed important for the future development of the device system.

A Model to Support Fluid Transitions between Environments for Mobile Augmented Reality Applications

The adaptability between different environments remains a challenge for Mobile Augmented Reality (MAR). If not done seamlessly, such transitions may cause discontinuities in navigation, consequently disorienting users and undermining the acceptance of this technology. The transition between environments is hard because there are currently no localization techniques that work well in any place: sensor-based applications can be harmed by obstacles that hamper sensor communication (e.g., GPS) and by infrastructure limitations (e.g., Wi-Fi), and image-based applications can be affected by lighting conditions that impair computer vision techniques. Hence, this paper presents an adaptive model to perform transitions between different types of environments for MAR applications. The model has a hybrid approach, choosing the best combination of long-range sensors, short-range sensors, and computer vision techniques to perform fluid transitions between environments that mitigate problems in location, orientation, and registration. To assess the model, we developed a MAR application and conducted a navigation test with volunteers to validate transitions between outdoor and indoor environments, followed by a short interview. The results show that the transitions were well succeeded, since the application self-adapted to the studied environments, seamlessly changing sensors when needed.

Effects of a Nutritional Supplement on Cognitive Function in Aged Dogs and on Synaptic Function of Primary Cultured Neurons

The objective of this research was to investigate the efficacy of DìSeniorTM, a nutraceutical formulated to improve cognitive functions in elderly dogs. To this purpose, some clinical and metabolic investigations and a spatial navigation test were performed in treated and untreated dogs. Moreover, the nutraceutical was also tested on primary hippocampal neuron cultures. Results showed no adverse effects on the dogs’ health and a positive effect on learning. In vitro effects on neuron cultures showed an increase in the level of cFOS in treated neurons compared with the vehicle, suggesting that DiSeniorTM has also a positive effect on neuronal functions. Overall, this study suggests that DiSeniorTM can exert a beneficial effect on aged dogs by preventing the negative effects of aging on cognition. Further studies are needed to assess the mechanisms by which it acts on neurons and the specific effect of the different components alone or combined.

A USABILITY EVALUATION OF A 3D MAP DISPLAY FOR PEDESTRIAN NAVIGATION

<p><strong>Abstract.</strong> This paper is focused to address the map display usability for finding given POI addresses in a popular urban city area. LOD 1 of 3D representations of city buildings are presented into a 2.5D map for pedestrian navigation test. This 3D map display is evaluated against familiar 2D map system on the test participants’ smartphones. 16 participants were involved in the field test. The typical walking model of a searching task that is focused only to look for a certain address of building is chosen as the way finding model during the field test. Three kinds of navigation processes i.e. self-orientation, spatial knowledge acquisition and navigation decision for searching task were evaluated for each test participant. Usability measures of 3D map-based display over 2D-map based display for pedestrian navigation were collected from test participants’ mobile devices. In addition to that, activities of test participants in terms of acceleration and orientation information are used to support analysis of pattern and trends of test participants. As the testing app is also intended to support smart city application, its ability to provide user report on complaints was also assessed. Most participants agreed with the statements in the questionnaire that were organized into three sections, i.e. addressing participants’ interaction, participants’ responses in navigation processes and crowdsensing. The results suggest that 3D map-based pedestrian navigation is more usable to be used to look for a certain address of building in central tourist area of urban city.</p>