Influence du traitement visuel sur la mémoire spatiale et les capacités de navigation des jeunes adultes et des personnes âgées

Healthy ageing is associated with a decline in spatial navigation abilities, resulting in a loss of mobility and autonomy. The majority of studies ascribes this decline solely to the deterioration of higher-level cognitive processes such as memory or executive functions, without considering age-related perceptual deficits. Yet, the way we in which we perceive visual information is key to engage adequately with the surrounding environment. This doctoral work aimed at understanding, via behavioural and neuroimaging measures, the impact of age-related changes in visual information encoding on spatial navigation abilities. In the first part of the thesis, we set out to establish the consequences of ageing on the use of visual spatial cues in the environment for orientation and navigation. In a functional magnetic resonance imaging (fMRI) experiment, we revealed a decline in spatial navigation performance in older adults associated with a specific reduction in the activity of parahippocampal regions involved in fine-grained information processing. The occipital place area (OPA) was recruited to a greater degree by older participants than young participants for reorientation. This visual area of the dorsal stream implicated in the encoding of scenes is also known to preferentially process information from the lower visual field. Results from this first part thus led us to hypothesise that the increased OPA activity could be driven partly by an age-related bias for the lower portion of the visual field. The second part of this work sought to test whether the vertical position of an object represents a fundamental property for spatial cognition in healthy older adults. In a computer-based experiment involving an object recognition task, we identified a spatial memory deficit in the upper visual field of older adults. Building on these results, we showed that this decline did not originate from age-related changes in the extent of visual fields or in the integrity of retinal layers. The third part of the thesis examined the cerebral correlates of processing the vertical position of landmarks in the context of more dynamic spatial navigation tasks. We first created a desktop-based navigation paradigm with eye tracking and electroencephalographic recordings to determine whether free visual search was associated with vertical biases. This experiment demonstrated a systematic bias among older adults for visual information in the lower portion of the screen as well as a modulation of theta and beta frequency bands as a function of object position. The latter results revealed that attention during navigation was not homogeneously distributed across the visual field in ageing. Finally, in a last spatial orientation experiment using fMRI, we showed that the OPA parsed the vertical position of useful information for navigation in young and older adults. We also found that the activation levels within the OPA were independent from its preference for the lower half of the visual field, and that they were more pronounced in older participants. Taken together, the results from this doctoral work highlighted the tight links between visual information processing and spatial cognition and they provided unique insights into the repercussions of visual ageing on navigational behaviour. This work also emphasised the importance of developing infrastructures tailored to older adults’ visuospatial preferences, with a view to maintaining their autonomy.Le vieillissement sain s’accompagne d’une diminution des capacités de navigation spatiale avec pour conséquence une perte de mobilité et d’autonomie. La majorité des études attribue cette atteinte uniquement au déclin de processus cognitifs, tels que la mémoire ou les fonctions exécutives, sans considérer les déficits perceptifs liés à l’âge. Or, la façon dont nous percevons l’information visuelle constitue une étape clé pour appréhender et agir sur notre environnement. Ce travail de thèse visait à comprendre, via des mesures comportementales et de neuroimagerie, l’impact du vieillissement du système de traitement de l’information visuelle sur les capacités de navigation spatiale. Le premier volet s’est attaché à évaluer les conséquences du vieillissement sur l’utilisation d’indices visuels pour l’orientation et la navigation spatiale. Dans une expérience en imagerie par résonance magnétique fonctionnelle (IRMf), nous avons montré une diminution des performances de navigation chez les participants âgés. Cette dernière était associée à une réduction de l’activité de régions parahippocampiques impliquées dans le traitement de l’information visuelle fine. L’occipital place area (OPA) était davantage sollicitée par les participants âgés que par les jeunes pour se réorienter. Cette région de la voie visuelle dorsale impliquée dans l’encodage de scènes a aussi pour particularité de traiter préférentiellement les informations du champ visuel inférieur. Les résultats de cette première partie nous ont ainsi permis d’émettre l’hypothèse que l’augmentation d’activité de l’OPA pourrait être associée à un biais, apparaissant avec l’âge, pour la portion inférieure du champ visuel. Le second volet de ce travail avait pour but de tester si le rôle de la position verticale d’un objet constituait une propriété essentielle pour la cognition spatiale des personnes âgées. Dans une expérience sur ordinateur impliquant une tâche de mémorisation d’objets, nous avons identifié un déficit spécifique de mémoire spatiale dans le champ visuel supérieur des personnes âgées. Forts de ce résultat, nous avons montré qu’un tel déclin n’était pas dû à des changements liés à l’âge de l’aire des champs visuels ou de l’intégrité des couches rétiniennes. Le troisième volet s’est intéressé aux corrélats neuraux du traitement de la position verticale d’objets dans le contexte de tâches de navigation plus écologiques. Nous avons d’abord créé une expérience de navigation sur ordinateur avec enregistrements oculomoteur et électroencéphalographique afin de déterminer si la recherche visuelle libre était associée à des biais verticaux. L’expérience a démontré un biais systématique chez les participants âgés pour l’information visuelle située dans la portion inférieure de l’écran ainsi qu’une modulation des bandes de fréquences theta et beta en fonction de la position de l’information. Ces résultats ont montré que l’attention n’était pas distribuée de manière homogène lors de la navigation au cours du vieillissement. Enfin, dans une dernière expérience d’orientation spatiale en IRMf, nous avons établi que l’OPA codait la position verticale d’objets utile à la navigation chez les participants jeunes et âgés. Nous avons aussi observé que l’activation de l’OPA était indépendante de son biais pour la partie basse du champ visuel, et qu’elle était plus prononcée chez les participants âgés. L’ensemble de ces travaux a permis de mettre en lumière les liens étroits qui existent entre traitement de l’information visuelle et cognition spatiale. Ce travail de thèse a contribué à une meilleure compréhension des répercussions du vieillissement visuel sur les comportements liés à l'orientation dans l'espace. Il a permis également de souligner l’importance d’une planification d’aménagement des infrastructures mieux adaptée aux caractéristiques visuo-spatiales des personnes âgées, dans une perspective de maintien de l’autonomie

Influence du traitement visuel sur la mémoire spatiale et les capacités de navigation des jeunes adultes et des personnes âgées

Le vieillissement sain s’accompagne d’une diminution des capacités de navigation spatiale avec pour conséquence une perte de mobilité et d’autonomie. La majorité des études attribue cette atteinte uniquement au déclin de processus cognitifs, tels que la mémoire ou les fonctions exécutives, sans considérer les déficits perceptifs liés à l’âge. Or, la façon dont nous percevons l’information visuelle constitue une étape clé pour appréhender et agir sur notre environnement. Ce travail de thèse visait à comprendre, via des mesures comportementales et de neuroimagerie, l’impact du vieillissement du système de traitement de l’information visuelle sur les capacités de navigation spatiale. Le premier volet s’est attaché à évaluer les conséquences du vieillissement sur l’utilisation d’indices visuels pour l’orientation et la navigation spatiale. Dans une expérience en imagerie par résonance magnétique fonctionnelle (IRMf), nous avons montré une diminution des performances de navigation chez les participants âgés. Cette dernière était associée à une réduction de l’activité de régions parahippocampiques impliquées dans le traitement de l’information visuelle fine. L’occipital place area (OPA) était davantage sollicitée par les participants âgés que par les jeunes pour se réorienter. Cette région de la voie visuelle dorsale impliquée dans l’encodage de scènes a aussi pour particularité de traiter préférentiellement les informations du champ visuel inférieur. Les résultats de cette première partie nous ont ainsi permis d’émettre l’hypothèse que l’augmentation d’activité de l’OPA pourrait être associée à un biais, apparaissant avec l’âge, pour la portion inférieure du champ visuel. Le second volet de ce travail avait pour but de tester si le rôle de la position verticale d’un objet constituait une propriété essentielle pour la cognition spatiale des personnes âgées. Dans une expérience sur ordinateur impliquant une tâche de mémorisation d’objets, nous avons identifié un déficit spécifique de mémoire spatiale dans le champ visuel supérieur des personnes âgées. Forts de ce résultat, nous avons montré qu’un tel déclin n’était pas dû à des changements liés à l’âge de l’aire des champs visuels ou de l’intégrité des couches rétiniennes. Le troisième volet s’est intéressé aux corrélats neuraux du traitement de la position verticale d’objets dans le contexte de tâches de navigation plus écologiques. Nous avons d’abord créé une expérience de navigation sur ordinateur avec enregistrements oculomoteur et électroencéphalographique afin de déterminer si la recherche visuelle libre était associée à des biais verticaux. L’expérience a démontré un biais systématique chez les participants âgés pour l’information visuelle située dans la portion inférieure de l’écran ainsi qu’une modulation des bandes de fréquences theta et beta en fonction de la position de l’information. Ces résultats ont montré que l’attention n’était pas distribuée de manière homogène lors de la navigation au cours du vieillissement. Enfin, dans une dernière expérience d’orientation spatiale en IRMf, nous avons établi que l’OPA codait la position verticale d’objets utile à la navigation chez les participants jeunes et âgés. Nous avons aussi observé que l’activation de l’OPA était indépendante de son biais pour la partie basse du champ visuel, et qu’elle était plus prononcée chez les participants âgés. L’ensemble de ces travaux a permis de mettre en lumière les liens étroits qui existent entre traitement de l’information visuelle et cognition spatiale. Ce travail de thèse a contribué à une meilleure compréhension des répercussions du vieillissement visuel sur les comportements liés à l'orientation dans l'espace. Il a permis également de souligner l’importance d’une planification d’aménagement des infrastructures mieux adaptée aux caractéristiques visuo-spatiales des personnes âgées, dans une perspective de maintien de l’autonomie.Healthy ageing is associated with a decline in spatial navigation abilities, resulting in a loss of mobility and autonomy. The majority of studies ascribes this decline solely to the deterioration of higher-level cognitive processes such as memory or executive functions, without considering age-related perceptual deficits. Yet, the way we in which we perceive visual information is key to engage adequately with the surrounding environment. This doctoral work aimed at understanding, via behavioural and neuroimaging measures, the impact of age-related changes in visual information encoding on spatial navigation abilities. In the first part of the thesis, we set out to establish the consequences of ageing on the use of visual spatial cues in the environment for orientation and navigation. In a functional magnetic resonance imaging (fMRI) experiment, we revealed a decline in spatial navigation performance in older adults associated with a specific reduction in the activity of parahippocampal regions involved in fine-grained information processing. The occipital place area (OPA) was recruited to a greater degree by older participants than young participants for reorientation. This visual area of the dorsal stream implicated in the encoding of scenes is also known to preferentially process information from the lower visual field. Results from this first part thus led us to hypothesise that the increased OPA activity could be driven partly by an age-related bias for the lower portion of the visual field. The second part of this work sought to test whether the vertical position of an object represents a fundamental property for spatial cognition in healthy older adults. In a computer-based experiment involving an object recognition task, we identified a spatial memory deficit in the upper visual field of older adults. Building on these results, we showed that this decline did not originate from age-related changes in the extent of visual fields or in the integrity of retinal layers. The third part of the thesis examined the cerebral correlates of processing the vertical position of landmarks in the context of more dynamic spatial navigation tasks. We first created a desktop-based navigation paradigm with eye tracking and electroencephalographic recordings to determine whether free visual search was associated with vertical biases. This experiment demonstrated a systematic bias among older adults for visual information in the lower portion of the screen as well as a modulation of theta and beta frequency bands as a function of object position. The latter results revealed that attention during navigation was not homogeneously distributed across the visual field in ageing. Finally, in a last spatial orientation experiment using fMRI, we showed that the OPA parsed the vertical position of useful information for navigation in young and older adults. We also found that the activation levels within the OPA were independent from its preference for the lower half of the visual field, and that they were more pronounced in older participants. Taken together, the results from this doctoral work highlighted the tight links between visual information processing and spatial cognition and they provided unique insights into the repercussions of visual ageing on navigational behaviour. This work also emphasised the importance of developing infrastructures tailored to older adults’ visuospatial preferences, with a view to maintaining their autonomy

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

International audienceOlder 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

An Appraisal of the Role of the Neocerebellum for Spatial Navigation in Healthy Aging

International audienceSpatial navigation is an intricate ability, requiring multisensory and motor integration, that is particularly impacted in aging. The age-related decline in navigational capabilities is known to be associated with changes in brain regions such as the frontal, temporal, and cerebellar cortices. Age-related cerebellar differences in spatial navigation have generally been ascribed to motor impairments, omitting the central role of this structure in several cognitive processes. In the present voxel-based morphometric study, we investigated gray matter volume loss in older adults across cognitive and motor subregions of the cerebellum. Specifically, we hypothesized that age-related gray matter differences would occur mainly in cerebellar regions involved in cognitive processing. Our results showed a significant age-related atrophy in the left neocerebellum of healthy older adults that includes Crus I and lobule VI. The latter are important nodes in the network that subtends cognitive abilities such as object recognition and spatial cognition. This exploratory work sets the ground for future research to investigate the extent of the neocerebellum's contribution to spatial navigation deficits in aging

Future trends in brain aging research: Visuo-cognitive functions at stake during mobility and spatial navigation

International audienceAging leads to a complex pattern of structural and functional changes, gradually affecting sensorimotor, perceptual, and cognitive processes. These multiscale changes can hinder older adults’ interaction with their environment, progressively reducing their autonomy in performing tasks relevant to everyday life. Autonomy loss can further be aggravated by the onset and progression of neurodegenerative disorders (e.g., age-related macular degeneration at the sensory input level; and Alzheimer’s disease at the cognitive level). In this context, spatial cognition offers a representative case of high-level brain function that involves multimodal sensory processing, postural control, locomotion, spatial orientation, and wayfinding capabilities. Hence, studying spatial behavior and its neural bases can help identify early markers of pathogenic age-related processes. Until now, the neural correlates of spatial cognition have mostly been studied in static conditions thereby disregarding perceptual (other than visual) and motor aspects of natural navigation. In this review, we first demonstrate how visuo-motor integration and the allocation of cognitive resources during locomotion lie at the heart of real-world spatial navigation. Second, we present how technological advances such as immersive virtual reality and mobile neuroimaging solutions can enable researchers to explore the interplay between perception and action. Finally, we argue that the future of brain aging research in spatial navigation demands a widespread shift toward the use of naturalistic, ecologically valid experimental paradigms to address the challenges of mobility and autonomy decline across the lifespan

The Vertical Position of Visual Information Conditions Spatial Memory Performance in Healthy Aging

Contains data and analysis scripts for: Durteste, M., Van Poucke, L., Combariza, S., Benziane, B., Sahel, J-A., Ramanoël, S. & Arleo, A. The Vertical Position of Visual Information Conditions Spatial Memory Performance in Healthy Aging. Communications Psychology (2023

Selective neural coding of object, feature, and geometry spatial cues in humans

International audienceOrienting in space requires the processing of visual spatial cues. The dominant hypothesis about the brain structures mediating the coding of spatial cues stipulates the existence of a hippocampal-dependent system for the representation of geometry and a striatal-dependent system for the representation of landmarks. However, this dual-system hypothesis is based on paradigms that presented spatial cues conveying either conflicting or ambiguous spatial information and that used the term landmark to refer to both discrete three-dimensional objects and wall features. Here, we test the hypothesis of complex activation patterns in the hippocampus and the striatum during visual coding. We also postulate that object-based and feature-based navigation are not equivalent instances of landmark-based navigation. We examined how the neural networks associated with geometry-, object-, and feature-based spatial navigation compared with a control condition in a two-choice behavioral paradigm using fMRI. We showed that the hippocampus was involved in all three types of cue-based navigation, whereas the striatum was more strongly recruited in the presence of geometric cues than object or feature cues. We also found that unique, specific neural signatures were associated with each spatial cue. Object-based navigation elicited a widespread pattern of activity in temporal and occipital regions relative to feature-based navigation. These findings extend the current view of a dual, juxtaposed hippocampal–striatal system for visual-spatial coding in humans. They also provide novel insights into the neural networks mediating object versus feature spatial coding, suggesting a need to distinguish these two types of landmarks in the context of human navigation

Anxiety symptoms and felt stigma among young people living with perinatally or behaviourally-acquired HIV in Ukraine: A cross-sectional survey.

BackgroundUkraine has the second largest European HIV epidemic. This study aimed to describe stigma, demographic and social factors and their association with anxiety among perinatally and behaviourally-HIV-infected (PHIV; BHIV) young people in Kiev and Odessa.Methods104 PHIV and 100 BHIV young people aged 13-25 years completed a confidential tablet-based survey. Survey tools included the Hospital Anxiety and Depression Scale (HADS) (anxiety sub-scale scores of 8-10 indicating mild and ≥11 moderate/severe symptoms in last 7 days), Rosenberg Self-Esteem Scale (RSES) and HIV Stigma Scale (HSS) (short version, composite of disclosure, negative self-image and public attitudes sub-scales). Unadjusted Poisson regression models were fitted to explore factors associated with moderate/severe anxiety symptoms.ResultsPHIV and BHIV young people were of median age 15.5 [IQR 13.9-17.1] and 23.0 [21.0-24.3] years, having registered for HIV care a median 12.3 [10.3-14.4] and 0.9 [0.2-2.4] years previously; 97% (97/100) and 66% (65/99) respectively were on ART. Overall 43% (95%CI 36-50%) reported any and 13% (95%CI 9-19%) moderate/severe anxiety symptoms, with no difference by HIV acquisition mode (p = 0.405) or gender (p = 0.700). 42% (75/180) reported history of an emotional health problem for which they had not been referred/attended for care. Moderate/severe anxiety symptoms were associated with HIV-related stigma (prevalence ratio (PR) 1.24 95%CI 1.14-1.34 per HSS unit increase), lower self-esteem (PR 0.83 95%CI 0.78-0.90 per RSES point increase), CD4 ≤350 cells/mm3 (PR 2.29 95%CI 1.06-4.97), having no-one at home who knew the respondent's HIV status (PR 9.15 95%CI 3.40-24.66 vs all know) and, among BHIV, less stable living situation (PR 6.83 95%CI 1.99-23.48 for ≥2 vs no home moves in last 3 years) and history of drug use (PR 4.65 95%CI 1.83-11.85).ConclusionsResults indicated unmet need for psychosocial support. Further work is needed to explore strategies for mental health support, particularly around disclosure, self-esteem and stigma