VALIDATION OF A MODEL OF SENSORIMOTOR INTEGRATION WITH CLINICAL BENEFITS

Healthy sensorimotor integration – or how our touch influences our movements – is critical to efficiently interact with our environment. Yet, many aspects of this process are still poorly understood. Importantly, several movement disorders are often considered as originating from purely motor impairments, while a sensory origin could also lead to a similar set of symptoms. To alleviate these issues, we hereby propose a novel biologically-based model of the sensorimotor loop, known as the SMILE model. After describing both the functional, and the corresponding neuroanatomical versions of the SMILE, we tested several aspects of its motor component through functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS). Both experimental studies resulted in coherent outcomes with respect to the SMILE predictions, but they also provided novel scientific outcomes about such broad topics as the sub-phases of motor imagery, the neural processing of bodily representations, or the extend of the role of the extrastriate body area. In the final sections of this manuscript, we describe some potential clinical application of the SMILE. The first one presents the identification of plausible neuroanatomical origins for focal hand dystonia, a yet poorly understood sensorimotor disorder. The last chapter then covers possible improvements on brain-machine interfaces, driven by a better understanding of the sensorimotor system. -- La façon dont votre sens du toucher et vos mouvements interagissent est connue sous le nom d’intégration sensorimotrice. Ce procédé est essentiel pour une interaction normale avec tout ce qui nous entoure. Cependant, plusieurs aspects de ce processus sont encore méconnus. Plus important encore, l’origine de certaines déficiences motrices encore trop peu comprises sont parfois considérées comme purement motrice, alors qu’une origine sensorielle pourrait mener à un même ensemble de symptômes. Afin d’améliorer cette situation, nous proposons ici un nouveau modèle d’intégration sensorimotrice, dénommé « SMILE », basé sur les connaissances de neurobiologie actuelles. Dans ce manuscrit, nous commençons par décrire les caractéristiques fonctionnelles et neuroanatomiques du SMILE. Plusieurs expériences sont ensuite effectuées, via l’imagerie par résonance magnétique fonctionnelle (IRMf), et la stimulation magnétique transcranienne (SMT), afin de tester différents aspects de la composante motrice du SMILE. Si les résultats de ces expériences corroborent les prédictions du SMILE, elles ont aussi mis en évidences d’autres résultats scientifiques intéressants et novateurs, dans des domaines aussi divers que les sous-phases de l’imagination motrice, les processus cérébraux liés aux représentations corporelles, ou encore l’extension du rôle de l’extrastriate body area. Dans les dernières parties de ce manuscrit, nous dévoilons quelques applications cliniques potentielles de notre modèle. Nous utilisons le SMILE afin de proposer deux origines cérébrales plausibles de la dystonie focale de la main. Le dernier chapitre présente comment certaines technologies existantes, telles que les interfaces cerveaux-machines, pourraient bénéficier d’une meilleure compréhension du système sensorimoteur

Biomimetic rehabilitation engineering: the importance of somatosensory feedback for brain-machine interfaces.

Brain-machine interfaces (BMIs) re-establish communication channels between the nervous system and an external device. The use of BMI technology has generated significant developments in rehabilitative medicine, promising new ways to restore lost sensory-motor functions. However and despite high-caliber basic research, only a few prototypes have successfully left the laboratory and are currently home-deployed. The failure of this laboratory-to-user transfer likely relates to the absence of BMI solutions for providing naturalistic feedback about the consequences of the BMI's actions. To overcome this limitation, nowadays cutting-edge BMI advances are guided by the principle of biomimicry; i.e. the artificial reproduction of normal neural mechanisms. Here, we focus on the importance of somatosensory feedback in BMIs devoted to reproducing movements with the goal of serving as a reference framework for future research on innovative rehabilitation procedures. First, we address the correspondence between users' needs and BMI solutions. Then, we describe the main features of invasive and non-invasive BMIs, including their degree of biomimicry and respective advantages and drawbacks. Furthermore, we explore the prevalent approaches for providing quasi-natural sensory feedback in BMI settings. Finally, we cover special situations that can promote biomimicry and we present the future directions in basic research and clinical applications. The continued incorporation of biomimetic features into the design of BMIs will surely serve to further ameliorate the realism of BMIs, as well as tremendously improve their actuation, acceptance, and use

Optimizing time-in-target-range assessment for blood pressure: insights from a large-scale study with continual cuffless monitoring

IntroductionBlood pressure (BP) time-in-target-range (TTR) is an emerging predictor of cardiovascular risk. Conventional BP methods are fundamentally unable to provide an optimal assessment of TTR, using irregular measurements separated by lengthy intervals. We investigated the optimal duration and frequency for reliable, practical TTR assessment in clinical settings using continual monitoring.MethodsThis retrospective study analyzed 2.3 million BP readings from 5,189 European home users (55 ± 11 years, 82% male, BMI 28.0 ± 5.8) using a cuffless BP monitor (Aktiia SA). Systolic BP (SBP) data over 15 consecutive days were assessed (29 ± 11 readings/subject/24-h; 434 + 132 readings/subject/15-day). Subjects were classified into risk-related TTR groups based on 15-day SBP data (24-h, target 90–125 mmHg; ≥6 daytime readings). Various measurement frequencies and durations (1–14 days; 24-h/daytime; 2, 4 or ≥ 6 readings/day) were compared to this reference. Two specific configurations paralleling ambulatory (“One-Day-24 h”) and home (“One-Week-Daytime”) BP monitoring were selected for detailed analysis.ResultsThe reference TTR classified 63.0% of the subjects as high risk, 19.0% intermediate, and 18.0% low. “One-Day-24 h” schedule inaccurately classified 26% of subjects compared to the reference TTR, and “One-Week-Daytime” schedule inaccurately classified 45%. Classification accuracy with both schedules was high for subjects with very low or very high reference TTR, but poor otherwise. Accuracy of ≥90% in TTR classification only occurred with 7 days of continual 24-h monitoring.DiscussionFor the first time, with the benefit of a cuffless device that measures BP with sufficient frequency and duration, practical use of TTR is enabled as a potentially enhanced metric to manage hypertension

Comparison of the Effects of Intermittent Boluses to Simple Continuous Infusion on Patients’ Global Perceived Effect in Intrathecal Therapy for Pain: A Randomized Double-Blind Crossover Study

Objective: Intrathecal drug delivery (ITDD) is commonly used for intractable pain management. A paucity of good quality studies in chronic non-cancer patients and concerns over increased dosages has focused interest on different modes of administration. The aim of this international multicentre randomised double-blind crossover trial was to compare the efficacy of the same daily dose of drugs administered by intermittent boluses versus simple continuous infusion. Methods: Eligible patients implanted with a programmable ITDD device were randomised to receive two weeks of either intermittent boluses or a simple continuous flow in period 1, followed by a crossover to the alternative mode of administration. The primary outcome measure was the Patients’ Global Impression of Change (PGIC) scale. Results: The mean proportion of positive responders (at least “minimally improved”) was 38.4% in the Continuous condition versus 37.3% in the Bolus (difference in proportions = 1.1%; 95% CI, -21.8 to 24.0%; P=0.93). The mean PGIC in the Continuous condition was 3.8 versus 3.9 in the Bolus (mean difference = -0.1; -0.6 to 0.4; P=0.72). Exploratory analyses revealed a tendency for the mean proportion of positive responders to be higher at low vs. high flow rates for both bolus and continuous administrations. Two patients were withdrawn from the study due to adverse events during the Bolus phase: both with symptoms of increased pain, and one patient with additional symptoms of numbness and urinary retention. Conclusion: The mean PGIC and proportion of positive responders was not substantially different after intermittent bolus versus continuous administration

Body Context and Posture Affect Mental Imagery of Hands

Different visual stimuli have been shown to recruit different mental imagery strategies. However the role of specific visual stimuli properties related to body context and posture in mental imagery is still under debate. Aiming to dissociate the behavioural correlates of mental processing of visual stimuli characterized by different body context, in the present study we investigated whether the mental rotation of stimuli showing either hands as attached to a body (hands-on-body) or not (hands-only), would be based on different mechanisms. We further examined the effects of postural changes on the mental rotation of both stimuli. Thirty healthy volunteers verbally judged the laterality of rotated hands-only and hands-on-body stimuli presented from the dorsum- or the palm-view, while positioning their hands on their knees (front postural condition) or behind their back (back postural condition). Mental rotation of hands-only, but not of hands-on-body, was modulated by the stimulus view and orientation. Additionally, only the hands-only stimuli were mentally rotated at different speeds according to the postural conditions. This indicates that different stimulus-related mechanisms are recruited in mental rotation by changing the bodily context in which a particular body part is presented. The present data suggest that, with respect to hands-only, mental rotation of hands-on-body is less dependent on biomechanical constraints and proprioceptive input. We interpret our results as evidence for preferential processing of visual- rather than kinesthetic-based mechanisms during mental transformation of hands-on-body and hands-only, respectively

Opportunities and drivers for green hydrogen production from renewable energy: Constructing of a causal loop diagram from stakeholders perspective in Iceland.

&amp;lt;p&amp;gt;Green hydrogen produced through electrolysis using renewable energy has the potential to decarbonize many sectors by replacing fossil fuels. Although production is currently marginal, green hydrogen projects are initiated and assessed all around the globe, ranging from small energy systems to large-scale production units. Previous studies have identified a wide range of key stakeholders that influence the diffusion of green hydrogen technologies. However, an understanding of the overall complexity of the emerging hydrogen sector regarding techno-economic, social, and environmental aspects is needed. The main objective of this study is to provide a depiction of an emerging sustainable technology sector by integrating various stakeholders&amp;amp;#8217; perspectives. Based on this mapping key mechanisms that foster or hinder the production of green hydrogen will be identified. To perform our study, we chose a green hydrogen production project at the Hellishei&amp;amp;#240;i geothermal power plant (Iceland) to construct a causal loop diagram (CLD) of the Icelandic green hydrogen production sector. Seven semi-structured interviews and one e-mail interview were conducted with relevant stakeholders. The National Innovation System was taken as a conceptual model in order to encourage the participants to answer in a systemic manner. Variables and causal links were then extracted from the interview transcripts using a coding process adapted from the literature. An overall CLD was constructed, showing the dynamic complexity of the system. The results show that mobility and export are the main sources for enhanced demand. Since most power companies in Iceland are state owned, green hydrogen supply comes mainly from energy companies, and strongly depends on political support. The importance of civil society, especially concerning the topics of nature protection and climate awareness, is also depicted. Additionally, a range of social, technical, and economical factors are identified, as well as their impact on the system&amp;amp;#8217;s behavior. The diagram allows for comprehension of stakeholders&amp;amp;#8217; expectations and concerns with their potential consequences on the diffusion on green hydrogen technologies. The use of system dynamics and causal loop modelling provides a comprehensive view on the problem and helps to address issues that could be overlooked without it. Some of these causal chains could potentially lead to policy failure if not addressed early enough. The findings can be used to enhance cooperation between stakeholders and guide decision-making processes.&amp;lt;/p&amp;gt;</jats:p

Differential neural encoding of sensorimotor and visual body representations

Sensorimotor processing specifically impacts mental body representations. In particular, deteriorated somatosensory input (as after complete spinal cord injury) increases the relative weight of visual aspects of body parts’ representations, leading to aberrancies in how images of body parts are mentally manipulated (e.g. mental rotation). This suggests that a sensorimotor or visual reference frame, respectively, can be relatively dominant in local (hands) versus global (full-body) bodily representations. On this basis, we hypothesized that the recruitment of a specific reference frame could be reflected in the activation of sensorimotor versus visual brain networks. To this aim, we directly compared the brain activity associated with mental rotation of hands versus full-bodies. Mental rotation of hands recruited more strongly the supplementary motor area, premotor cortex, and secondary somatosensory cortex. Conversely, mental rotation of full-bodies determined stronger activity in temporo-occipital regions, including the functionally-localized extrastriate body area. These results support that (1) sensorimotor and visual frames of reference are used to represent the body, (2) two distinct brain networks encode local or global bodily representations, and (3) the extrastriate body area is a multimodal region involved in body processing both at the perceptual and representational level.ISSN:2045-232