Vision artificielle pour les non-voyants : une approche bio-inspirée pour la reconnaissance de formes

More than 315 million people worldwide suffer from visual impairments, with several studies suggesting that this number will double by 2030 due to the ageing of the population. To compensate for the loss of sight the current approaches consist of either specific aids designed to answer particular needs or generic systems such as neuroprostheses and sensory substitution devices. These holistic approaches, which try to restore vision as a whole, have been shown to be very inefficient in real life situations given the low resolution of output interfaces. To overcome these obstacles we propose the use of artificial vision in order to pre-process visual scenes and provide the user with relevant information. We have validated this approach through the development of a novel assistive device for the blind called Navig. Through shape recognition and spatialized sounds synthesis, this system allows users to locate and grab objects of interest. It also features navigational aids based on a new positioning method combining GPS, inertial sensors and the visual detection of geolocalized landmarks. To enhance the performance of the visual module we further developed, as part of this thesis, a bio-inspired pattern recognition algorithm which uses latency-based coding of visual information, oriented edge representations and a cascaded architecture combining detection at different resolutions.La déficience visuelle touche aujourd’hui plus de 315 millions de personnes à travers le monde, un chiffre qui pourrait doubler d’ici à 2030 du fait du vieillissement de la population. Les deux grandes approches existantes pour compenser la perte de vision sont les aides spécifiques, répondant à un besoin identifié, et les systèmes génériques tels que les neuroprothèses ou les systèmes de substitution sensorielle. Ces approches holistiques, tentant de restituer l’ensemble de l’information visuelle, s’avèrent inadaptées de par la trop faible résolution des interfaces de sortie, rendant ces systèmes inutilisables dans la vie quotidienne. Face à ce constat, nous proposons dans cette thèse une démarche alternative, consistant à intégrer des méthodes de vision artificielle, afin de prétraiter la scène visuelle, et de ne restituer au non-voyant que les informations extraites pertinentes. Pour valider cette approche, nous présenterons le développement d’un système de suppléance baptisé Navig. Grâce à la reconnaissance de formes et à la synthèse de sons spatialisés, il permet à l’utilisateur de localiser des objets d’intérêt. Il offre également des fonctions de navigation, basées sur une nouvelle méthode de positionnement combinant GPS, données inertielles, et détections de cibles visuelles géolocalisées. Afin d’améliorer les performances du module de vision artificielle, nous proposerons également dans cette thèse un nouvel algorithme de reconnaissance de formes bio-inspiré, reposant sur un codage de l’information visuelle par latence, sur des représentations sous forme d’arêtes orientées, et sur une architecture en cascade combinant des détections à différentes résolutions

Validation of the repetitive and restricted behaviour scale in autism spectrum disorders

Repetitive and restricted behaviours represent a common problem for various psychiatric syndromes, especially in autistic spectrum disorders, and they include a wide range of heterogeneous behavioural manifestations. An accurate and standardized description of these behaviours is needed to advance the understanding of this complex and heterogeneous clinical dimension of autism. The present article reports the reliability and validity studies of a new assessment scale: the repetitive and restricted behaviour scale. 145 subjects with autism spectrum disorders were assessed using the RRB scale. The RRB scale has good interrater reliability, internal consistency and content validity. Factorial analysis produced four clinically meaningful factors, i.e. “sensorimotor stereotypies”, “reaction to change”, “restricted behaviours” and “modulation insufficiency”. The RRB scale has good psychometric qualities and constitutes a real breakthrough towards a neurofunctional approach to autistic disorders. It should be valuable for research and treatment, and in clinical practice

Total knee arthroplasty in valgus knee

SummaryTotal knee arthroplasty (TKA) in valgus knee has the reputation of being more difficult than in well aligned or varus knee, and there is no management consensus. Results on a continuous series of 100 TKAs on valgus knee were compared to the literature data, to define surgical strategy adapted to the various types of valgus knee

Les compléments neurophysiologiques du diagnostic

Neurophysiological complements of autism diagnosis Research presented show relationships between behavioral and cognitive disorders and underlying cerebral functional abnormalities, on the basis of non invasive electrophysiological investigations (electroencephalography, cortical evoked potentials). Three types of disturbances are studied: sleep problems, intolerance to change and atypical visual processing of human faces. The complementarity of clinical and neurophysiological approaches is crucial at the levels of functional diagnosis, therapeutic and educative interventions

Digital Continuity Based on Reinforcement Learning Model Transformation

With the importance gained by Service-Oriented Architectures (SOA) to simplify and decompose complex enterprise information system into autonomous, modular, reusable and, flexible model, the need to make models interoperable to ensure digital continuity has increased. However, the structural, syntactic, and semantic heterogeneity of metamodel, drastically complicates the interconnection of models and thus the digital continuity. A key element of Model-Driven Architecture (MDA), model transformations could be one of the solutions to promote model interoperability. They allow the description of the transformation rules that link the different metamodels concepts. However, significant efforts are needed to describe and maintain model transformations in an ever-changing digital environment. One of the key challenges of the MDA approach is the automation of model transformations. Recent work exploiting machine learning techniques to infer model transformations has shown very promising results. However, learning algorithms, involve too much training data and require a large and varied dataset. In our work, we want to experiment the reinforcement learning techniques to infer transformation rules and to counter the need to provide a considerable volume of data for machine learning.Financement : CNES et Thales Alenia Spac

Cranio-Facial Characteristics in Autism Spectrum Disorder: A Scoping Review

Autism spectrum disorders (ASD) consist of a complex group of neurodevelopmental disorders characterised by qualitative impairments of social interactions, communication abilities, and a limited, stereotyped, and repetitive selection of interests and activities. In light of the imperative to identify a possible biomarker for ASD, it has been determined that craniofacial anomalies serve as significant risk factors for neurodevelopmental disorders. The aim of this scoping review is to deepen the knowledge of the scientific literature related to cranio-facial characteristics in individuals with ASD, with a particular focus on recent research advancements. The review was performed by employing the search strings (("Autism Spectrum Disorder" OR autism OR ASD OR "Autism Spectrum") AND ("facial morphology" OR "facial phenotype")) on the databases PubMed/MEDLINE, Scopus, and ERIC as of March 9, 2023. The review comprised seven studies whose findings were obtained through quantitative analysis of Euclidean distances between anatomical landmarks. The examination of facial abnormalities represents a possible reliable diagnostic biomarker that could aid in the timely identification of ASD. Phenotypic characteristics that may serve as predictive indicators of the severity of autistic symptoms can be observed in certain individuals with ASD by applying anthropometric and instrumental measurements. The presence of a phenotype characterised by an increased intercanthal distance and a reduced facial midline height appears to be associated with a higher degree of severity in autistic symptoms. In addition, it is worth noting that facial asymmetry and facial masculinity can be considered reliable indicators for predicting a more severe manifestation of symptoms

Neural repetition suppression to vocal and non-vocal sounds

Adaptation to the sensory environment is essential in everyday life, to anticipate future events and quickly detect and respond to changes; and to distinguish vocal variations in congeners, for communication. The aim of the current study was to explore the effects of the nature (vocal/non-vocal) of the information to be encoded, on the establishment of auditory regularities. In electrophysiology, neural adaptation is measured by the ‘Repetition Positivity’ (RP), which refers to an increase in positive potential, with the increasing number of repetitions of a same stimulus. The RP results from the combined variation of several ERP components; the P1, the first positivity (∼100 ms) may reflect the onset of repetition effects. We recorded auditory evoked potentials during a roving paradigm in which trains of 4, 8 or 16 repetitions of the same stimulus were presented. Sequences of vocal and non-vocal complex stimuli were delivered, to study the influence of the type of stimulation on the characteristics of the brain responses. The P1 to each train length, and the RP responses were recorded between 90 and 200 ms, reflecting adaptation for both vocal and non-vocal stimuli. RP was not different between vocal and non-vocal sequences (in latency, amplitude and spatial organization) and was found to be similar to that found in previous studies using pure tones, suggesting that the repetition suppression phenomena is somehow independent of the nature of the stimulus. However, results showed faster stabilization of the P1 amplitude for non vocal stimuli than for vocal stimuli, which require more repetitions. This revealed different dynamics for the establishment of regularity encoding for non-vocal and vocal stimuli, indicating that the richness of vocal sounds may require further processing before full neural adaptation occurs

Total ankle arthroplasty - total ankle arthroplasty in Western France: influence of volume on complications and clinical outcome

INTRODUCTION: Total ankle arthroplasty (TAA) has become an alternative to ankle arthrodesis in the treatment of advanced osteoarthritis. "The difficulty of performing a total ankle replacement and the corresponding steep learning curve" has resulted in a proposal "to limit ankle replacement to centers that have performed at least ten total ankle replacements for at least 3 years". The aim of this study was to evaluate the influence of the frequency of TAA procedures on the complications and outcome of these arthroplasties. MATERIALS AND METHODS: This retrospective series included 183 cases who underwent surgery between 1997-2010 in eight centers: three high volume centers performed at least five TAA per year (100 cases) and six low volume centers performed less than five TAA per year (78 cases). RESULTS: The clinical assessment was performed in 133 cases that were reviewed after a mean 39 months ± 29 of follow-up. The preoperative AOFAS score was 33 ± 4 and 77 ± 15 at the final follow-up. The five-year survival rate was 86%. No significant difference was found between the groups for the AOFAS score or implant survival at the final follow-up. The high volume centers experienced more complications (45% versus 13%) but fewer implant failures (8% versus 13%) overall compared to the low volume centers. DISCUSSION: The outcome of TAA depends mainly upon the pertinence of the indication and the associated procedures that may be necessary. Rather than limiting TAA to high volume reference centers, we suggest that the assessment of each case within a predetermined area should be done in a network. This would determine the degree of specialization required for each TAA case and provide all patients with safe and equal access to this therapeutic option. LEVEL OF EVIDENCE: IV - Retrospective study

Functional morphological imaging of autism spectrum disorders: Current position and theories proposed

AbstractAutism is a pervasive disorder of childhood development. Polymorphous clinical profiles combining various degrees of communication and social interaction with restricted and stereotyped behaviour are grouped under the heading of ‘autism spectrum disorders’ (ASD). Many teams are trying to pick out the underlying cerebral abnormalities in order to understand the neuronal networks involved in relationships with others. Here we review the morphological, spectroscopic and functional abnormalities in the amygdala-hippocampal circuit, the caudate nuclei, the cerebellum, and the frontotemporal regions, which have been described in subjects with ASD. White matter abnormalities have also been described in diffusion tensor imaging, leading to suspected damage to the subjacent neural networks, such as mirror neurones or the social brain

1H-13C NMR-based urine metabolic profiling in autism spectrum disorders.

International audienceAutism Spectrum Disorders (ASD) are a group of developmental disorders caused by environmental and genetic factors. Diagnosis is based on behavioral and developmental signs detected before 3 years of age with no reliable biological marker. The purpose of this study was to evaluate the potential use of a 2D NMR-based approach to express the global biochemical signature of autistic individuals compared to normal controls. This technique has greater spectral resolution than to 1D (1)H NMR spectroscopy, which is limited by overlapping signals. The urinary metabolic profiles of 30 autistic and 28 matched healthy children were obtained using a (1)H-(13)C NMR-based approach. The data acquired were processed by multivariate orthogonal partial least-squares discriminant analysis (OPLS-DA). Some discriminating metabolites were identified: β-alanine, glycine, taurine and succinate concentrations were significatively higher, and creatine and 3-methylhistidine concentrations were lower in autistic children than in controls. We also noted differences in several other metabolites that were unidentified but characterized by a cross peak correlation in (1)H-(13)C HSQC. Statistical models of (1)H and (1)H-(13)C analyses were compared and only 2D spectra allowed the characterization of statistically relevant changes [R(2)Y(cum)=0.78 and Q(2)(cum)=0.60] in the low abundance metabolites. This method has the potential to contribute to the diagnosis of neurodevelopment disorders but needs to be validated on larger cohorts and on other developmental disorders to define its specificity