Missing the egocentric spatial reference: a blank on the map

Evaluation of Mental Rotation Ability in Patients with Unilateral Benign Paroxysmal Positional Vertigo

BACKGROUND

Our study aims to determine whether there are differences in mental rotation abilities between unilateral benign paroxysmal positional vertigo patients and healthy controls using object-based mental rotation tasks.

METHODS

Our study included 17 unilateral posterior canal benign paroxysmal positional vertigo patients and 20 healthy adults. Spontaneous nystagmus test, saccade test, and dynamic positional tests with videonystagmography and object-based mental rotation test with 2-dimensional images of cubes rotated at certain angles in 3-dimensional space were performed on the participants. The mental rotation test response time and the number of correct answers were compared between patients and controls. We also evaluated whether there was a relationship between saccade test parameters and mental rotation test parameters in our study.

RESULTS

No significant relationship was found between benign paroxysmal positional vertigo patients and controls on any of the dependent measures (P -gt; .05). When we evaluated the relationship between saccadic latency and accuracy and mental rotation test response time and number of correct answers in benign paroxysmal positional vertigo patients, no significant relationship was found (P -gt; .05).

CONCLUSION

Our findings show that unilateral, posterior canal benign paroxysmal positional vertigo does not affect object-based mental rotation performance. In our study, no correlation was found between saccadic function and mental rotation ability in unilateral benign paroxysmal positional vertigo patients.

Assessing cognitive decline in the aging brain: lessons from rodent and human studies

As life expectancy continues to increase worldwide, age-related dysfunction will largely impact our societies in the future. Aging is well established to promote the deterioration of cognitive function and is the primary risk factor for the development of prevalent neurological disorders. Even in the absence of dementia, age-related cognitive decline impacts specific types of memories and brain structures in humans and animal models. Despite this, preclinical and clinical studies that investigate age-related changes in brain physiology often use largely different methods, which hinders the translational potential of findings. This review seeks to integrate what is known about age-related changes in the brain with analogue cognitive tests used in humans and rodent studies, ranging from "pen and paper" tests to virtual-reality-based paradigms. Finally, we draw parallels between the behavior paradigms used in research compared to the enrollment into clinical trials that aim to study age-related cognitive decline.

Reconfiguration of brain network dynamics underlying spatial deficits in subjective cognitive decline

Brain dynamics and the associations with spatial navigation in individuals with subjective cognitive decline (SCD) remain unknown. In this study, a hidden Markov model (HMM) was inferred from resting-state functional magnetic resonance imaging data in a cohort of 80 SCD and 77 normal control (NC) participants. By HMM, 12 states with distinct brain activity were identified. The SCD group showed increased fractional occupancy in the states with less activated ventral default mode, posterior salience, and visuospatial networks, while decreased fractional occupancy in the state with general network activation. The SCD group also showed decreased probabilities of transition into and out of the state with general network activation, suggesting an inability to dynamically upregulate and downregulate brain network activity. Significant correlations between brain dynamics and spatial navigation were observed. The combined features of spatial navigation and brain dynamics showed an area under the curve of 0.854 in distinguishing between SCD and NC. The findings may provide exploratory evidence of the reconfiguration of brain network dynamics underlying spatial deficits in SCD.

Tibolone Improves Memory and Decreases the Content of Amyloid-β Peptides and Tau Protein in the Hippocampus of a Murine Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) affects women more than men and consequently has been associated with menopause. Tibolone (TIB) has been used as a hormone replacement therapy to alleviate climacteric symptoms. Neuroprotective effects of TIB have also been reported in some animal models.

OBJECTIVE

This study aimed to assess the effect of TIB on memory and Aβ peptides and tau protein content in the hippocampus and cerebellum of transgenic 3xTgAD ovariectomized mice.

METHODS

Three-month-old female mice were ovariectomized. Ten days after surgery, animals were divided into four groups: wild-type (WT)+vehicle; WT+TIB (1 mg/kg); 3xTgAD+vehicle; and 3xTgAD+TIB (1 mg/kg). TIB was administered for three months, and memory was evaluated using the object-in-context recognition task. Subsequently, animals were decapitated, and the hippocampus and cerebellum were dissected. Using commercial ELISA kits, these brain structures were homogenized in a PBS buffer for quantifying Aβ40 and Aβ42 and phosphorylated and total tau.ResultsA long-term memory deficit was observed in the 3xTgAD+vehicle group. In contrast, TIB treatment improved long-term memory in the 3xTgAD+TIB group than those treated with vehicle (p < 0.05). Furthermore, TIB treatment decreased Aβ and tau content in the hippocampus of 3xTgAD mice compared to vehicle-treated groups (p < 0.05). No significant changes were observed in the cerebellum.

CONCLUSION

Chronic treatment with TIB showed neuroprotective effects and delayed AD neuropathology in the 3xTgAD mice. Our results support hormone replacement therapy with TIB in menopausal women for neuroprotection.

Egocentric norm in health-based decision making of patients on the autistic spectrum

BACKGROUND

Individuals diagnosed with autism spectrum disorder (ASD) without intellectual disability (ID) may have advanced mental reasoning; however, symptomology may vary within the population. Possible symptomology includes communication problems, difficulty relating to people, things, and events, and sensory sensitivity. Current concepts in determining health behavior are not applicable to the ASD without ID population.

AIM

The aim of this analysis is to define the concept of egocentric norm in the context of health-based decisions of adults diagnosed with ASD without ID and to support improved nursing practice with this population.

DESIGN

The Walker and Avant approach was used. Model, borderline, and contrary cases are offered.

DATA SOURCE

Literature search yielded 47 peer reviewed papers that were included in the analysis.

REVIEW METHODS

Uses of the concept were reviewed, following the Walker and Avant approach.

RESULTS

Egocentric norm is defined as an individual's ability to perceive, adapt, and respond to information and potential consequences of personal health behavior based on self-evaluation and the immediate environment with limited regard to peer and family influence.

CONCLUSIONS

The new concept of egocentric norm may account for the unique dynamics presented by adults with ASD without ID, which may impact health behaviors and actions.

Two Immersive Virtual Reality Tasks for the Assessment of Spatial Orientation in Older Adults with and Without Cognitive Impairment: Concurrent Validity, Group Comparison, and Accuracy Results

OBJECTIVE

Spatial disorientation is common in Alzheimer's disease (AD), Mild Cognitive Impairment (MCI), and preclinical individuals with AD biomarkers. However, traditional neuropsychological tests lack ecological validity for the assessment of spatial orientation and to date, there is still no gold standard. The current study aimed to determine the validity and accuracy of two virtual reality tasks for the assessment of spatial orientation.

METHODS

We adapted two spatial orientation tasks to immersive virtual environments: a "survey to route" task in which participants had to transfer information from a map to their body position within a maze [Spatial Orientation in Immersive Virtual Environment Test (SOIVET) Maze], and an allocentric-type, route learning task, with well-established topographic landmarks (SOIVET Route). A total of 19 MCI patients and 29 cognitively healthy older adults aged 61-92 participated in this study. Regular neuropsychological assessments were used for correlation analysis and participant performances were compared between groups. Receiver Operating Characteristic (ROC) curve analysis was performed for accuracy.

RESULTS

The SOIVET Maze correlated with measures of visuoperception, mental rotation, and planning, and was not related to age, educational level, or technology use profile. The SOIVET Route immediate correlated with measures of mental rotation, memory, and visuoconstruction, and was influenced only by education. Both tasks significantly differentiated MCI and control groups, and demonstrated moderate accuracy for the MCI diagnosis.

CONCLUSION

Traditional neuropsychological assessment presents limitations and immersive environments allow for the reproduction of complex cognitive processes. The two immersive virtual reality tasks are valid tools for the assessment of spatial orientation and should be considered for cognitive assessments of older adults.

Palmitoylated prolactin-releasing peptide reduced Aβ plaques and microgliosis in the cerebellum: APP/PS1 mice study

BACKGROUND

Prolactin-releasing peptide (PrRP) is a potential drug for the treatment of obesity and associated type 2 diabetes mellitus (T2DM) due to its strong anorexigenic and antidiabetic properties. In our recent study, the lipidized PrRP analog palm11-PrRP31 was proven to exert beneficial effects in APP/PS1 mice, a model of Alzheimer´s disease (AD)-like amyloid-β (Aβ) pathology, reducing the Aβ plaque load, microgliosis and astrocytosis in the hippocampus and cortex.

OBJECTIVE

In this study, we focused on the neuroprotective and anti-inflammatory effects of palm11-PrRP31 and its possible impact on synaptogenesis in the cerebellum of APP/PS1 mice, because others have suggested that cerebellar Aβ plaques contribute to cognitive deficits in AD.

METHODS

APP/PS1 mice were treated subcutaneously with palm11-PrRP31 for 2 months, then immunoblotting and immunohistochemistry were used to quantify pathological markers connected to AD, compared to control mice.

RESULTS

In the cerebella of 8 months old APP/PS1 mice, we found widespread Aβ plaques surrounded by activated microglia detected by ionized calcium-binding adapter molecule (Iba1), but no increase in astrocytic marker glial fibrillary acidic protein (GFAP) compared to controls. Interestingly, no difference in both presynaptic markers syntaxin1A and postsynaptic marker spinophilin was registered between APP/PS1 and control mice. Palm11-PrRP31 treatment significantly reduced the Aβ plaque load and microgliosis in the cerebellum. Furthermore, palm11-PrRP31 increased synaptogenesis and attenuated neuroinflammation and apoptosis in the hippocampus of APP/PS1 mice.

CONCLUSION

These results suggest palm11-PrRP31 is a promising agent for the treatment of neurodegenerative disorders.

Egocentric and Allocentric Reference Frames Can Flexibly Support Contextual Cueing

We investigated if contextual cueing can be guided by egocentric and allocentric reference frames. Combinations of search configurations and external frame orientations were learned during a training phase. In Experiment 1, either the frame orientation or the configuration was rotated, thereby disrupting either the allocentric or egocentric and allocentric predictions of the target location. Contextual cueing survived both of these manipulations, suggesting that it can overcome interference from both reference frames. In contrast, when changed orientations of the external frame became valid predictors of the target location in Experiment 2, we observed contextual cueing as long as one reference frame was predictive of the target location, but contextual cueing was eliminated when both reference frames were invalid. Thus, search guidance in repeated contexts can be supported by both egocentric and allocentric reference frames as long as they contain valid information about the search goal.

A Thalamic Reticular Circuit for Head Direction Cell Tuning and Spatial Navigation

As we navigate in space, external landmarks and internal information guide our movement. Circuit and synaptic mechanisms that integrate these cues with head-direction (HD) signals remain, however, unclear. We identify an excitatory synaptic projection from the presubiculum (PreS) and the multisensory-associative retrosplenial cortex (RSC) to the anterodorsal thalamic reticular nucleus (TRN), so far classically implied in gating sensory information flow. In vitro, projections to TRN involve AMPA/NMDA-type glutamate receptors that initiate TRN cell burst discharge and feedforward inhibition of anterior thalamic nuclei. In vivo, chemogenetic anterodorsal TRN inhibition modulates PreS/RSC-induced anterior thalamic firing dynamics, broadens the tuning of thalamic HD cells, and leads to preferential use of allo- over egocentric search strategies in the Morris water maze. TRN-dependent thalamic inhibition is thus an integral part of limbic navigational circuits wherein it coordinates external sensory and internal HD signals to regulate the choice of search strategies during spatial navigation.

Ego- and allo-network disconnection underlying spatial disorientation in subjective cognitive decline

Patients with Alzheimer's disease (AD) related dementia and mild cognitive impairment experience difficulties with spatial navigation (SN). However, SN has rarely been investigated in individuals with subjective cognitive decline (SCD), a preclinical stage with elevated progression rate to symptomatic AD. In this study, 30 SCD subjects and 30 controls underwent cognitive scale (CS) evaluation, a 2D computerized SN test, and resting-state functional magnetic resonance imaging scanning. Two SN brain networks (ego-network and allo-network), each with 10 selected spherical regions, were defined. We calculated the average network functional connectivity (FC) and region-to-region FC within the two networks and evaluated correlations with SN performance. Compared with the controls, the SCD group performed worse in the SN test and showed decreased FC between the right retrosplenial and right prefrontal cortices in the ego-network, and between the right retrosplenial cortex and right hippocampus in the allo-network. The logistic regression model based on SN and FC measures revealed a high area under the curve of .880 in differentiating SCD individuals from controls. These results suggest that SN network disconnection contributes to spatial deficits in SCD, and SN and FC measures could benefit the preclinical detection of subjects with incipient AD dementia.

Wayfinding in People with Alzheimer’s Disease: Perspective Taking and Architectural Cognition—A Vision Paper on Future Dementia Care Research Opportunities

Based on a targeted literature review, this vision paper emphasizes the importance of dementia-sensitive built space. The article specifically focuses on supporting spatial orientation and wayfinding for people living with dementia. First, we discuss types of wayfinding challenges, underlying processes, and consequences of spatial disorientation in the context of dementia of the Alzheimer’s type. Second, we focus on current efforts aimed at planning and evaluating dementia-sensitive built space, i.e., environmental design principles, interventions, evaluation tools, strategies, and planning processes. Third, we use our findings as a starting point for developing an interdisciplinary research vision aimed at encouraging further debates and research about: (1) the perspective of a person with dementia, specifically in the context of wayfinding and spatial orientation, and (2) how this perspective supplements planning and design processes of dementia-sensitive built space. We conclude that more closely considering the perspective of people with dementia supports the development of demographically sustainable future cities and care institutions.

Differential Brain Activity in Regions Linked to Visuospatial Processing During Landmark-Based Navigation in Young and Healthy Older Adults

Older adults have difficulties in navigating unfamiliar environments and updating their wayfinding behavior when faced with blocked routes. This decline in navigational capabilities has traditionally been ascribed to memory impairments and dysexecutive function, whereas the impact of visual aging has often been overlooked. The ability to perceive visuospatial information such as salient landmarks is essential to navigating efficiently. To date, the functional and neurobiological factors underpinning landmark processing in aging remain insufficiently characterized. To address this issue, functional magnetic resonance imaging (fMRI) was used to investigate the brain activity associated with landmark-based navigation in young and healthy older participants. The performances of 25 young adults (μ = 25.4 years, σ = 2.7; seven females) and 17 older adults (μ = 73.0 years, σ = 3.9; 10 females) were assessed in a virtual-navigation task in which they had to orient using salient landmarks. The underlying whole-brain patterns of activity as well as the functional roles of specific cerebral regions involved in landmark processing, namely the parahippocampal place area (PPA), the occipital place area (OPA), and the retrosplenial cortex (RSC), were analyzed. Older adults' navigational abilities were overall diminished compared to young adults. Also, the two age groups relied on distinct navigational strategies to solve the task. Better performances during landmark-based navigation were associated with increased neural activity in an extended neural network comprising several cortical and cerebellar regions. Direct comparisons between age groups revealed that young participants had greater anterior temporal activity. Also, only young adults showed significant activity in occipital areas corresponding to the cortical projection of the central visual field during landmark-based navigation. The region-of-interest analysis revealed an increased OPA activation in older adult participants during the landmark condition. There were no significant between-group differences in PPA and RSC activations. These preliminary results hint at the possibility that aging diminishes fine-grained information processing in occipital and temporal regions, thus hindering the capacity to use landmarks adequately for navigation. Keeping sight of its exploratory nature, this work helps towards a better comprehension of the neural dynamics subtending landmark-based navigation and it provides new insights on the impact of age-related visuospatial processing differences on navigation capabilities.

Spatial navigation ability is associated with the assessment of smoothness of driving during changing lanes in older drivers

Background

Age-related changes affect driving ability, including the smoothness of driving. This operation requires the use of both allocentric strategies (based on world-centered representations) and egocentric strategies (based on self-centered representations); however, with age, a greater preference for egocentric strategies is evident when driving. Furthermore, an age-related decline occurs in both driving ability and spatial navigation. We therefore assessed the relationship between spatial navigation and driving smoothness and tested whether a driving simulator can be used to evaluate smooth lane changes in older drivers.

Methods

A total of 34 healthy older drivers (mean age: 68.2 ± 5.4 years old) and 20 younger drivers (mean age = 20.2 ± 5.4 years old) participated in this study. The smoothness of driving was assessed using a driving simulator and spatial navigation was assessed using the Card-Placing Test-A/B. We also assessed visual perception and general intellectual function using standard neuropsychological tests.

Results

Older drivers had significantly worse spatial navigation and exhibited less smooth driving than younger drivers. Furthermore, we found a negative correlation between the smoothness of driving and spatial navigation within both groups. These results suggest that the deterioration in spatial navigation in older people may underlie the observed decrease in driving smoothness, and that spatial navigation and smooth driving deteriorate with age.

Conclusions

Considering these results, we found a significant correlation in the older group between the smoothness of vehicle movement and spatial navigation, in the smoothness of vehicle movement between the young and old groups. The smoothness values, which indices thoroughly derived from the driving simulator are indeed showing some evidence in ego/allocentric cognitions, which may change by age. The driving simulator could aid the development of intervention programs or assessment measures for drivers with a decreased function.

Flexible use of allocentric and egocentric spatial memories activates differential neural networks in mice

Goal-directed navigation can be based on world-centered (allocentric) or body-centered (egocentric) representations of the environment, mediated by a wide network of interconnected brain regions, including hippocampus, striatum and prefrontal cortex. The relative contribution of these regions to navigation from novel or familiar routes, that demand a different degree of flexibility in the use of the stored spatial representations, has not been completely explored. To address this issue, we trained mice to find a reward relying on allocentric or egocentric information, in a modified version of the cross-maze task. Then we used Zif268 expression to map brain activation when well-trained mice were required to find the goal from a novel or familiar location. Successful navigation was correlated with the activation of CA1, posterior-dorsomedial striatum, nucleus accumbens core and infralimbic cortex when allocentric-trained mice needed to use a novel route. Allocentric navigation from a familiar route activated dorsomedial striatum, nucleus accumbens, prelimbic and infralimbic cortex. None of the structures analyzed was significantly activated in egocentric-trained mice, irrespective of the starting position. These data suggest that a flexible use of stored allocentric information, that allows goal finding even from a location never explored during training, induces a shift from fronto-striatal to hippocampal circuits.

Protocol for a conversation-based analysis study: PREVENT-ED investigates dialogue features that may help predict dementia onset in later life

INTRODUCTION

Decreasing the incidence of Alzheimer's disease (AD) is a global public health priority. Early detection of AD is an important requisite for the implementation of prevention strategies towards this goal. While it is plausible that patients at the early stages of AD may exhibit subtle behavioural signs of neurodegeneration, neuropsychological testing seems unable to detect these signs in preclinical AD. Recent studies indicate that spontaneous speech data, which can be collected frequently and naturally, provide good predictors for AD detection in cohorts with a clinical diagnosis. The potential of models based on such data for detecting preclinical AD remains unknown.

METHODS AND ANALYSIS

The PREVENT-Elicitation of Dialogues (PREVENT-ED) study builds on the PREVENT Dementia project to investigate whether early behavioural signs of AD may be detected through dialogue interaction. Participants recruited through PREVENT, aged 40-59 at baseline, will be included in this study. We will use speech processing and machine learning methods to assess how well speech and visuospatial markers agree with neuropsychological, biomarker, clinical, lifestyle and genetic data from the PREVENT cohort.

ETHICS AND DISSEMINATION

There are no expected risks or burdens to participants. The procedures are not invasive and do not raise significant ethical issues. We only approach healthy consenting adults and all participants will be informed that this is an exploratory study and therefore has no diagnostic aim. Confidentiality aspects such as data encryption and storage comply with the General Data Protection Regulation and with the requirements from sponsoring bodies and ethical committees. This study has been granted ethical approval by the London-Surrey Research Ethics Committee (REC reference No: 18/LO/0860), and by Caldicott and Information Governance (reference No: CRD18048). PREVENT-ED results will be published in peer-reviewed journals.

The Emerging Role of Altered Cerebellar Synaptic Processing in Alzheimer's Disease

The role of the cerebellum in Alzheimer's disease (AD) has been neglected for a long time. Recent studies carried out using transgenic mouse models have demonstrated that amyloid-β (Aβ) is deposited in the cerebellum and affects synaptic transmission and plasticity, sometimes before plaque formation. A wide variability of motor phenotype has been observed in the different murine models of AD, without a consistent correlation with the extent of cerebellar histopathological changes or with cognitive deficits. The loss of noradrenergic drive may contribute to the impairment of cerebellar synaptic function and motor learning observed in these mice. Furthermore, cerebellar neurons, particularly granule cells, have been used as in vitro model of Aβ-induced neuronal damage. An unexpected conclusion is that the cerebellum, for a long time thought to be somehow protected from AD pathology, is actually considered as a region vulnerable to Aβ toxic damage, even at the early stage of the disease, with consequences on motor performance.