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While the impact of the gut microbiota on brain and behavior is increasingly recognized, human studies examining this question are still scarce. The primary objective of the current study was to explore the potential relationships between the gut microbiota composition, motor cortical excitability at rest and during inhibitory control, as well as behavioral inhibition, in healthy volunteers and in patients suffering from alcohol use disorder. Motor cortical excitability was examined using a range of transcranial magnetic stimulation (TMS) measures probed at rest, including the recruitment curve, short and long intracortical inhibition, and intracortical facilitation within the primary motor cortex. Moreover, TMS was applied during a choice reaction time task to assess changes in motor excitability associated with inhibitory control. Finally, behavioral inhibition was investigated using a neuropsychological task (anti-saccade). Overall, our results highlight several interesting correlations between microbial composition and brain measures. Hence, higher bacterial diversity, as well as higher relative abundances of UGC-002 and Christensenellaceae R-7 group were correlated with stronger changes in motor excitability associated with inhibitory control. Also, higher abundance of Anaerostipes was associated with higher level of corticospinal excitability. Finally, relative abundances of Bifidobacterium and Faecalibacterium were positively related to performance in the neuropsychological task, suggesting that they might have a positive impact on behavioral inhibition. Although correlation is not causation, the present study suggests that excitatory and inhibitory brain processes might be related to gut microbiota composition.

Pain typically evolves over time and the brain needs to learn this temporal evolution to predict how pain is likely to change in the future and orient behavior. This process is termed temporal statistical learning (TSL). Recently, it has been shown that TSL for pain sequences can be achieved using optimal Bayesian inference, which is encoded in somatosensory processing regions. Here, we investigate whether the confidence of these probabilistic predictions modulates the EEG response to noxious stimuli, using a TSL task. Confidence measures the uncertainty about the probabilistic prediction, irrespective of its actual outcome. Bayesian models dictate that the confidence about probabilistic predictions should be integrated with incoming inputs and weight learning, such that it modulates the early components of the EEG responses to noxious stimuli, and this should be captured by a negative correlation: when confidence is higher, the early neural responses are smaller as the brain relies more on expectations/predictions and less on sensory inputs (and vice versa). We show that participants were able to predict the sequence transition probabilities using Bayesian inference, with some forgetting. Then, we find that the confidence of these probabilistic predictions was negatively associated with the amplitude of the N2 and P2 components of the Vertex Potential: the more confident were participants about their predictions, the smaller was the Vertex Potential. These results confirm key predictions of a Bayesian learning model and clarify the functional significance of the early EEG responses to nociceptive stimuli, as being implicated in confidence-weighted statistical learning.

Lower-limb exoskeletons are wearable devices whose main purposes are human rehabilitation and bilateral locomotion assistance. In particular, there is a growing interest for their use to symmetrize the gait of hemiparetic patients. This often consists in using the kinematics of the less affected side as a reference for the most affected one. In this work, we followed this approach to design a symmetrization algorithm using the formalism of motor primitives, i.e. a low-dimensional set of signals that provide the desired assistance through their combination. The amount of variables to be stored in memory is thus intrinsically limited, and this framework is particularly adapted to include other modes of assistance and/or transitions between locomotion tasks. In this paper, we report the preliminary validation of this newly developed algorithm with a hip exoskeleton and a single participant replicating hemiparetic walking. Results show that the algorithm effectively managed to reduce both temporal and spatial gait asymmetry

Part of the multifaceted pathophysiology of Complex Regional Pain Syndrome (CRPS) is ascribed to lateralized maladaptive neuroplasticity in sensorimotor cortices, corroborated by behavioral studies indicating that patients present difficulties in mentally representing their painful limb. Such difficulties are widely measured with hand laterality judgment tasks (HLT), which are also used in the rehabilitation of CRPS to activate motor imagery and restore the cortical representation of the painful limb. The potential of these tasks to elicit motor imagery is critical to their use in therapy, yet, the influence of the body's biomechanical constraints (BMC) on HLT reaction time, supposed to index motor imagery activation, is rarely verified. Here we investigated the influence of BMC on the perception of hand postures and movements in upper-limb CRPS. Patients were slower than controls in judging hand laterality, whether or not stimuli corresponded to their painful hand. Reaction time patterns reflecting BMC were mostly absent in CRPS and controls. A second experiment therefore directly investigated the influence of implicit knowledge of BMC on hand movement judgments. Participants judged the perceived path of movement between two depicted hand positions, with only one of two proposed paths that was biomechanically plausible. While the controls mostly chose the biomechanically plausible path, patients did not. These findings show non-lateralized body representation impairments in CRPS, possibly related to difficulties in using correct knowledge of the body's biomechanics. Importantly, they demonstrate the challenge of reliably measuring motor imagery with the HLT, which has important implications for the rehabilitation with these tasks.

Objective The aim of this observational longitudinal study was to investigate the impact of lifestyle factors on the prognosis of patients with pain. Methods This study was part of a large prospective longitudinal study conducted in general practice (GP). Participants completed questionnaires at baseline (T0) and one year later (T1). Outcomes analysed were the EQ-5D index, presence of pain and the ability to perform a light work for 1 hour without difficulty. Results Among 377 individuals with pain at T0, 294 still reported pain at T1. This subgroup had a significantly higher BMI, more painful sites, higher pain intensity, more sleep problems, poorer general self-rated health (GSRH) and higher Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) score at T0 than pain-free individuals at T1. There were no differences in age, sex, physical activity and smoking. In multivariable analyses, the number of painful sites, GSRH, sleep problems, pain duration, pain intensity and 2 short-form 10-item Örebro musculoskeletal pain questionnaire (SF-ÖMPSQ) items were independently associated with at least one outcome 1 year later. Only GSRH was strongly associated with all outcomes. The accuracy of GSRH at T0 to classify participants according to dichotomous outcomes was overall moderate (0.7 < AUC <0.8). Conclusions Lifestyle factors appear to have little influence on the outcome of patients with pain in GP. Conversely, poorer GSRH – which probably integrates the subjects’ perception of several factors – could be considered a negative prognostic factor in patients with pain.

The aim of my project was to develop and apply focused ultrasound stimulation (FUS) to study the human brain. Recently, TFUS was proposed as an advantageous alternative technique for non-invasive modulation of human brain activity. Compared to transcranial magnetic stimulation and transcranial direct current stimulation, the two most-used techniques for neuromodulation, TFUS is more focal and allow to target deeper brain structures with a reduced effect on surrounding cortical tissue. I first determined the sonication parameters to use according to international safety guidelines. Then, I used the prototype I designed to characterize the effects of TFUS sonication over the primary somatosensory cortex using somatosensory-evoked potentials elicited by transcutaneous electrical stimulation of the median nerve (MN). We report the successful modulation of early SEPs potentials (N20 and P27) for TFUS applied 200ms before the delivery of MN stimulation., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2023

Motor learning allows animals, including human beings, to acquire skills that are essential for efficient interactions with the environment. This ability to learn new motor skills is of great practical relevance for daily-life activities (such as when learning to drive), but also for motor rehabilitation after a lesion of the nervous system (such as a stroke). For a long time, motor learning has been mainly conceptualized as a process allowing to iteratively correct movements based on sensory information (e.g., visual, somatosensory). Importantly though, in the last years, there has been an increased appreciation that motor learning also results from other mechanisms including reinforcement learning, a process through which appropriate actions are selected through outcome-based feedback (e.g., success or failure). As such, recent evidence shows that reinforcement feedback and mo-tivation can be beneficial for motor learning both in healthy individuals and neurological populations. Despite the potential importance of these findings to improve current rehabil-itation protocols, the mechanisms underlying reinforcement-related improvements in mo-tor learning remain largely unexplored. This PhD aimed at providing deeper mechanistic understanding of reinforcement learning of motor skills through behavioral analyses, neuroimaging and non-invasive brain stimulation. In Study 1, I found that enhancing motivation (by providing monetary reward for good performance) during a motor training can lead to persistent improvements in performance that are not obtained with reinforce-ment feedback only, and are related to an increased regulation of motor variability based on previous outcomes. In Study 2, I investigated the effect of reward timing (i.e., the delay between the end of movement execution and reward receipt) on motor learning and found that delaying reward by only a few seconds could strongly influence motor learning dynamics and consolidation. Finally, in Study 3, I inves, (MED - Sciences médicales) -- UCL, 2023

In Parkinson’s disease, neurophysiological abnormalities within the primary motor cortex have been shown to contribute to cardinal symptoms such as bradykinesia, but the exact modalities are still uncertain. Here, we propose that such impairment could involve alterations of mechanisms shaping motor activity specifically during voluntary movement preparation. Indeed, several past studies in healthy populations have suggested that a strong suppression of corticospinal excitability called “preparatory suppression” – propels movement execution by increasing motor neural gain. Thus, we hypothesized that a gradual alteration to this mechanism may contribute to progressive motor slowness in Parkinson’s disease. We also predicted a benefit of dopamine medication in restoring correct motor neural activity during action preparation. To test these hypotheses, we investigated preparatory suppression on two consecutive days in 29 Parkinson’s disease patients (ON and OFF medication) and 29 matched healthy controls. Single-pulse transcranial magnetic stimulation was applied over both primary motor cortices, eliciting concurrent motor-evoked potentials in the two hands, while subjects were either at rest or prepared a left- or right-hand response in an instructed-delay choice reaction time task. Preparatory suppression was assessed by expressing the amplitude of motor potentials evoked during movement preparation relative to those obtained at rest. These neurophysiological measures were cross-analysed with task behaviour and clinical data. Contrary to healthy controls, Parkinson’s disease patients showed a lack of preparatory suppression, which appeared to depend on disease progression, but not on dopamine medication. Indeed, in relatively early disease stages, patients still exhibited partial preparatory suppression, while in later stages, they lacked it completely and even exhibited a tendency for corticospinal facilitation in the hand selected for movement execution. As expected

BACKGROUND: Physical exercise therapy is of proven efficacy in the treatment of adults with depression, but corresponding evidence is lacking in depressed adolescent inpatients. The aim of this study was to document the effect of add-on treatment with structured physical exercise in a clinical population of adolescents hospitalized for depression and anxiety in a psychiatric hospital. METHODS: A group of 52 adolescent inpatients was randomly assigned to a physical exercise or control program three to four times per week over a six-week period (20 hours in total). The primary outcome was the Hospital Anxiety Depression Scale (HADS) for evaluation of depression and anxiety symptoms. Secondary outcomes were psychological self-assessments, diagnostic interviews, and physical examinations. RESULTS: Six participants were lost in each group, leaving 20 inpatients each in the intervention and control groups. A linear mixed model with F-test revealed a significant interaction in favor of physical exercise in reducing the mean depression score (HADS-D) by 3.8 points [95% (CI), range 1.8 to 5.7], compared to a mean reduction score of 0.7 [95% (CI), range -0,7 to 2.0] in the control group. No significant interaction was found for anxiety symptoms (HADS-A). LIMITATIONS: The investigation was limited to the six-week hospital window and the small sample size prevented exploring differences in social characteristics. CONCLUSION: Structured physical exercise add-on therapy integrated into the psychiatric hospitalization of adolescents has led to a reduction in their depressive symptoms, demonstrating its effectiveness in the care of adolescent inpatients with depression.

Visual and proprioceptive feedback both contribute to perceptual decisions, but it remains unknown how these feedback signals are integrated together or consider factors such as delays and variance during online control. We investigated this question by having participants reach to a target with randomly applied mechanical and/or visual disturbances. We observed that the presence of visual feedback during a mechanical disturbance did not increase the size of the muscle response significantly but did decrease variance, consistent with a dynamic Bayesian integration model. In a control experiment, we verified that vision had a potent influence when mechanical and visual disturbances were both present but opposite in sign. These results highlight a complex process for multisensory integration, where visual feedback has a relatively modest influence when the limb is mechanically disturbed, but a substantial influence when visual feedback becomes misaligned with the limb. NEW & NOTEWORTHY Visual feedback is more accurate, but proprioceptive feedback is faster. How should you integrate these sources of feedback to guide limb movement? As predicted by dynamic Bayesian models, the size of the muscle response to a mechanical disturbance was essentially the same whether visual feedback was present or not. Only under artificial conditions, such as when shifting the position of a cursor representing hand position, can one observe a muscle response from visual feedback.

Errors and their consequences are typically studied by investigating changes in decision speed and accuracy in trials that follow an error, commonly referred to as “post-error adjustments”. Many studies have reported that subjects slow down following an error, a phenomenon called “post-error slowing” (PES). However, the functional significance of PES is still a matter of debate as it is not always adaptive. That is, it is not always associated with a gain in performance and can even occur with a decline in accuracy. Here, we hypothesized that the nature of PES is influenced by one’s speed-accuracy tradeoff policy, which determines the overall level of choice accuracy in the task at hand. To test this hypothesis, we investigated post-error adjustments in subjects performing the same task while they were required to either emphasize speed (low accuracy) or cautiousness (high accuracy) in two distinct contexts (hasty and cautious contexts, respectively) experienced on separate days. Accordingly, our data indicate that post-error adjustments varied according to the context in which subjects performed the task, with PES being solely significant in the hasty context. In addition, we only observed a gain in performance after errors in a specific trial type, suggesting that post-error adjustments depend on a complex combination of processes that affect the speed of ensuing actions as well as the degree to which such PES comes with a gain in performance.

Previous studies suggest that humans are capable of coregulating the speed of decisions and movements if promoted by task incentives. It is unclear however whether such behavior is inherent to the process of translating decisional information into movements, beyond posing a valid strategy in some task contexts. Therefore, in a behavioral online study we imposed time constraints to either decision or movement -phases of a sensorimotor task, ensuring that coregulating decisions and movements was not promoted by task incentives. We found that participants indeed moved faster when fast decisions were promoted and decided faster when subsequent movements had to be executed swiftly. Furthermore, inflicting faster movements seems to alter decision-making in a similar fashion as conditions promoting faster decisions: In both fast-decision and fast-movement blocks, decisions relied more strongly on information presented shortly rather than long before movement onset. Taken together, these findings suggest that decisions not only impact movement characteristics, but that properties of movement impact the time and manner with which decisions are made. We interpret these behavioral results in the context of embodied decision-making, whereby shared neural mechanisms may not only enable faster movements but also assist in making decisions in less time.

Behavioural studies have suggested that number manipulation involves shifting attention along a left-to-right oriented continuum. However, these studies provide little evidence about the time course of attention shifts during number processing. We used an eye-tracker with high spatio-temporal resolution to measure eye movements during the mental solving of addition (e.g., 43 + 4) and subtraction problems (e.g., 53 − 6), as a proxy for the rightward and leftward attention shifts that accompany these operations. A first difference in eye position was observed as soon as the operator was heard: the hearing of “plus” shifted the eye rightward compared to “minus”. A second difference was observed later between problem offset and response onset: addition shifted the eye rightward and upward compared to subtraction, suggesting that the space used to represent the problem is bidimensional. Further analyses confirmed the fast deployment of spatial attention and evidenced its relationship with the carrying and borrowing procedures triggered by the problem presentation. The predictive role of horizontal eye movements, in particular, is essential to understand how attention contributes to narrow down the range of plausible answers. We propose that attention illuminates significant portions of the numerical continuum anticipatively to guide the search of the answer and facilitate the implementation of solving procedures in verbal working memory.

The pupil light response is more than a pure reflexive mechanism that reacts to the amount of light entering the eye. The pupil size may also react to the luminance of objects lying in the visual periphery, revealing the locus of covert attention. In the present study, we took advantage of this response to study the spatial coding of abstract concepts with no physical counterpart: numbers. The participants’ gaze was maintained fixed in the middle of a screen whose left and right parts were dark or bright, and variations in pupil size were recorded during an auditory number comparison task. The results showed that small numbers accentuated pupil dilation when the darker part of the screen was on the left, while large numbers accentuated pupil dilation when the darker part of the screen was on the right. This finding provides direct evidence for covert attention shifts on a left-to-right oriented mental spatial representation of numbers. From a more general perspective, it shows that the pupillary response to light is subject to modulation from spatial attention mechanisms operating on mental contents.

Most of our interactions with the world occur through reaching movements. These movements were extensively studied in the past decades and revealed rich mechanisms both during planning and execution. Despite these numerous years of research, very little is known about the entanglement between the planning and execution facets of reaching movements. This thesis explores the interactions between the planning and execution steps of these reaching movements through a combination of experimental and modeling approaches. First, we demonstrate that the control policies selected to execute movements are not immutable and can be adjusted online to accommodate changes in task demands. These online adjustments suggest the existence of a mechanism whereby changes in the task could elicit replanning of movement. Elaborating on this first finding, we then report that this adjustment can also handle dynamical changes in the task. This finding reinforces the first one as it demonstrates that this adjustment mechanism consists in a continuous feedback loop monitoring task demands to optimally adjust the control policy online. Then, we reveal that selecting more robust control policy, intended at rejecting potential disturbances, reduces flexibility during movement. This last result demonstrates a competition between movement vigor and flexibility. This work adds to the understanding of the control policies underlying reaching movements by providing new insights into the interactions between movement planning and execution. These results, combined with the modeling work, highlight the fact that movement planning and execution are, (FSA - Sciences de l'ingénieur) -- UCL, 2022

Movements establish intended outcomes in the environment. To set these goals of movement, a plethora of brain process, often termed ‘cognition’, spell out the intended course of action. Articles investigating whether and when cognitive and motor functions may interact, and which brain regions may be responsible for their integration, are featured in the Research Topic ‘Mechanisms Underlying the Interplay Between Cognition and Motor Control: From Bench to Bedside’. In this Editorial, we summarize these empirical and theoretical findings and draw four main conclusions: 1) Cognition and movement likely follow similar overarching goals and hence are subject to common regulatory mechanisms. 2) Cognition and movement share neural resources implicated in a broad range of motor and cognitive functions. 3) Cognition is likely central for movement control: Matching predicted and perceived sensory outcomes of own movement reveals whether movement is effective in establishing intended outcomes or requires correction. 4) Movement-related brain activity may be utilized for cognitive functions: Simulating movement may promote accurate sensory predictions, which may then be utilized for abstract operations such as planning, inference or thinking. In short, we provide a brief introduction for the idea that cognition and movement operate as direct functions of each other.

Background and aims Previous studies have shown that High Frequency electrical Stimulation (HFS) of skin nociceptors can produce an increase in sensitivity to mechanical pinprick stimuli attributed to long-term potentation within spinal nociceptive pathway and, possibly, increased excitability within supra spinal relays leading to the primary somatosensory cortex S1. Here, we aimed at characterizing the relationship between HFS-induced secondary hyperalgesia and changes in brain activity at rest. To do so, we compared the frequency content of resting state EEG before and after HFS. The analyses focused on the signals measured over S1, as previously hypothesized to witness central sensitization phenomenon within resting state EEG. Methods HFS was delivered to the right volar forearm of 32 healthy participants. The electrode consisted of 10 blunt tungsten pins with a diameter of 0.25 mm protruding 0.65 mm from the base (MRC Systems). The stimulation consisted of five 100 Hz trains of square-wave pulses delivered every 10 seconds during one second. Sensitivity to pinprick stimulation (128 mN) was evaluated before and 30 minutes after HFS using a Numerical Rating Scale (NRS) ranging from 0 (no perception) to 100 (most intense imaginable pain) with 50 as the anchor between non-painful and painful sensation. We used the average of 3 successive ratings for statistical analysis. Resting state EEG (60 sec eyes closed to enhance alpha-band amplitude, 64 channels, 1 kHz sampling rate) was recorded before and 30 minutes after HFS. The spectral content was analyzed offline using a Fast Fourier Transform (FFT) on halfoverlapping 5 seconds segments. The amplitude of four different frequency bands were analyzed after averaging the signal from the left and right central electrodes C3-C4 : delta (0–4 Hz), theta (4-8 Hz, alpha (8–12 Hz) and beta (12-30 Hz). One tailed paired-sample t-tests were used to assess differences in the maximum amplitude within these frequency bands before ver

Reward timing, that is, the delay after which reward is delivered following an action is known to strongly influence reinforcement learning. Here, we asked if reward timing could also modulate how people learn and consolidate new motor skills. In 60 healthy participants, we found that delaying reward delivery by a few seconds influenced motor learning. Indeed, training with a short reward delay (1 s) induced continuous improvements in performance, whereas a long reward delay (6 s) led to initially high learning rates that were followed by an early plateau in the learning curve and a lower performance at the end of training. Participants who learned the skill with a long reward delay also exhibited reduced overnight memory consolidation. Overall, our data show that reward timing affects the dynamics and consolidation of motor learning, a finding that could be exploited in future rehabilitation programs.

Among the various control laws developed for lower-limb wearable robotics, several intend to replicate leg joint moments observed in healthy humans. While this can be achieved by different means, inspiration can be gained from the so-called motor primitives, i.e. a small set of fundamental signals used by the nervous system to recruit numerous motor pools in a task-specific way. Here we report a methodology for the extraction of constrained-shape primitives. Stimulations of two antagonist hip muscles are initially retrieved from a database composed of different locomotion tasks. A first guess of the primitives parameters is then performed in order to reconstitute these stimulations. Finally these parameters are optimized with the aim of retrieving the original database moments. Our findings suggest that a small number of symmetric Gaussian-like periodic primitives may reconstruct these hip moments with a level of fidelity that would be sufficient for providing a task-specific user support.

This paper reports the development of a novel compliant controller for a transfemoral prosthesis that combines a feed-forward prediction torque component with a feedback error correction. The controller architecture aims to track primitive-based reference trajectories by the prosthetic joints. It relies on Locally Weighted Projection Regression, a function approximator that acts as an inverse internal model of the prosthesis. The proposed strategy is validated in a simulation environment.

Vision based systems for terrain detection play important roles in mobile robotics, and recently such systems emerged for locomotion assistance of disabled people. For instance, they can be used as wearable devices to assist blind people or to guide prosthesis or exoskeleton controller to retrieve gait patterns being adapted to the executed task (overground walking, stairs, slopes, etc.). In this paper, we present a computer vision-based algorithm achieving the detection of flat ground, steps, and ramps using a depth camera. Starting from point cloud data collected by the camera, it classifies the environment as a function of extracted features. We further provide a pilot validation in an indoor environment containing a rich set of different types of terrains, even with partial occlusion, and observed that the overall system accuracy is above 94$$\%$$%. The paper further shows that our system needs less computational resources than recently published concurrent approaches, owing to the original transformation method we developed.

This paper overviews our recent efforts for promoting adaptive oscillators as template for modeling and assisting rhythmic movements. Adaptive oscillators are dynamical systems that can be viewed as the simplest possible model of a neural Central Pattern Generator, augmented with learning dynamics. Therefore, if coupled to a human user producing a rhythmic movement, such an adaptive oscillator can be used to govern the behavior of an assistive robot providing different kinds of rhythmic movement support, with or without energy injection, and both for the upper- and the lower-limb. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Previous studies have shown that judgments about how one would perform an action are affected by the current body posture. Hence, judging the capability to grasp an object between finger and thumb is influenced by their aperture at the time of the judgment. This finding can be explained by a modification of the internal representation of one’s hand through the effect of sensorimotor input. Alternatively, the influence of grip aperture might be mediated by a response congruency effect, so that a “less” vs. “more” open grip would bias the judgment toward a “less” vs. “more” capable response. To specify the role of sensorimotor input in prospective action judgments, we asked participants to estimate their capability to grasp circles between index and thumb while performing a secondary task that requires them to squeeze a ball with these two fingers (precision grip) or with a different hand configuration (palm grip). Experiment 1 showed that participants underestimated their grasping capability when the squeezing task involved the same grip as the judged action (precision grip) and their estimates were bound to the relative size of objects as revealed by size-contrast illusions (Ebbinghaus). Experiment 2 showed that the grip reduction caused by the squeezing task also interfered with the discrimination of large numbers in magnitude judgments, but this incongruency effect was only observed for the palm grip. The dissociated effects of the two grips in graspability and numerical judgments indicate that sensorimotor input may affect the perceived ability to grasp objects, independently of response congruency, by modifying the representation of the hand in action.

Few new drugs have been developed for chronic pain. Drug development is challenged by uncertainty about whether the drug engages the human target sufficiently to have a meaningful pharmacodynamic effect. IMI2-PainCare-BioPain-RCT1 is one of four similarly designed studies that aim to link different functional biomarkers of drug effects on the nociceptive system that could serve to accelerate the future development of analgesics. This study focusses on biomarkers derived from nerve excitability testing (NET) using threshold tracking of the peripheral nervous system. This is a multisite single-dose, subject and assessor-blind, randomized, placebo-controlled, 4-period, 4-way crossover, pharmacodynamic (PD), and pharmacokinetic (PK) study in healthy subjects. Biomarkers derived from NET of large sensory and motor fibers and small sensory fibers using perception threshold tracking will be obtained before and three times after administration of three medications known to act on the nociceptive system (lacosamide, pregabalin, tapentadol) and placebo, given as a single oral dose with at least 1 week apart. Motor and sensory NET will be assessed on the right wrist in a non-sensitized normal condition while perception threshold tracking will be performed bilaterally on both non-sensitized and sensitized forearm skin. Cutaneous high-frequency electrical stimulation is used to induce hyperalgesia. Blood samples will be taken for pharmacokinetic purposes and pain ratings as well as predictive psychological traits will be collected. A sequentially rejective multiple testing approach will be used with overall alpha error of the primary analysis split across the two primary outcomes: strength-duration time constant (SDTC; a measure of passive membrane properties and nodal persistent Na conductance) of large sensory fibers and SDTC of large motor fibers comparing lacosamide and placebo. The key secondary endpoint is the SDTC measured in small sensory fibers. Remaining treatment arm

Conflicting results exist between somatosensory profiles of patients with temporomandibular myalgia (TMDm). The objective of this review was to examine whether adults with TMDm show altered responses to dynamic quantitative sensory tests compared with healthy controls. We searched five electronic databases for studies, excluding those without suitable controls or where TMDm was associated with confounding non-musculoskeletal disorders. Risk of bias was assessed with the SIGN case-control study checklist. Findings were structured around dynamic quantitative sensory tests and their localization. Where possible, we performed meta-analysis with a random inverse variance model to compare patients with TMDm and healthy controls. Statistical heterogeneity was estimated with Chi² test and inconsistency index, I². We extracted data from 23 studies comprising 1284 adults with chronic TMDm and 2791 healthy controls. Risk of bias was assessed as high for 20 studies. Mechanical temporal summation, the most studied phenomenon (14 studies), is increased in the upper limb of patients with TMDm (SMD = 0.43; 95% CI: .11 to .75; p = .009) but not in the jaw area (p = .09) or in the cervical area (p = .29). Very little evidence for altered thermal temporal summation (five studies), conditioned pain modulation (seven studies), exercise-induced hypoalgesia (two studies), placebo analgesia (two studies), stress-induced hypoalgesia (one study) and offset analgesia (one study) was found. A major limitation of this review was the risk of bias of included studies. Future studies would benefit from following methodological guidelines and consideration of confounding factors.

Central sensitization is thought to play a critical role in the development of chronic pain, and secondary mechanical hyperalgesia is considered one of its hall-mark features. Consequently, interventions capable of modulating its development could have important therapeutic value. Non-invasive neuromodulation of the left dorsolateral prefrontal cortex (DLPFC) has shown potential to reduce pain, both in healthy volunteers and in patients. Whether it can modulate the induction of central sensitization, however, is less well known. To determine whether multifocal transcranial direct current stimulation (tDCS) targeting the left DLPFC affects the development of secondary mechanical hyperalgesia. In this within-subjects, cross-over, double-blinded study, eighteen healthy volunteers participated in three experimental sessions. After 20 minutes of either anodal, cathodal, or sham multichannel tDCS over the left DLPFC, secondary mechanical hyperalgesia was induced using high-frequency electrical stimulation (HFS) of the volar forearm. We assessed intensity of perception to 128 mN mechanical pinprick stimuli at baseline and up to 240 minutes after HFS. We also mapped the area of mechanical hyperalgesia. HFS resulted in a robust and unilateral increase in the intensity of perception to mechanical pinprick stimuli at the HFS arm, which was not different between tDCS stimulation conditions. However, the area of hyperalgesia was reduced after anodal tDCS compared to sham. Anodal tDCS over the left DLPFC modestly modulates the size of the HFS-induced area of secondary mechanical hyperalgesia, suggesting that non-invasive neuromodulation targeting the left DLPFC may be a potential intervention to limit the development of central sensitization.

The somatotopic interface (SI) and non-somatotopic interface (NI) are commonly used to provide non-invasive sensory feedback. Nevertheless, differences between somatotopic and non-somatotopic feedbacks are rarely reported, and objective evaluations of the corresponding brain response are missing as well. Few studies have reported how to design the stimulation encoding strategy based on the two interfaces in sensory feedback. The objective of this study was to investigate the difference in sensory characteristics between SI and NI, and propose an optimal encoding method for non-invasive feedback interfaces.. We recruited seven amputees and compared the tactile sensitivity to stimulated positions and intensities between SI (phantom finger area) and NI (upper arm) in a tactile discrimination task. Electroencephalography (EEG) evaluation task was subsequently conducted to objectively evaluate the stimulus-evoked brain response for SI and NI. Finally, the two kinds of tactile information (stimulated position and intensity) was applied to an object recognition task in a closed-loop prosthesis control system. Specifically, the object size was reflected by the prosthetic finger position through stimulated position encoding, and the object stiffness was reflected by the contact force of prosthetic fingers through stimulated intensity encoding. We compared the performance under four feedback conditions (combinations between two kinds of tactile information and two interfaces).. Behavioral results showed that NI was more sensitive to position information while SI was more sensitive to intensity information. EEG results were consistent with behavioral results, showing a higher sensitivity of sensory alpha ERD and a stronger correlation between alpha ERD and discrimination accuracies for NI in the position discrimination, while the trend was opposite in the intensity discrimination. The feedback encoding allowed amputees to discriminate the size and stiffness of nine objects w

Target reward influences motor planning strategies through modulation of movement vigor. Considering current theories of sensorimotor control suggesting that movement planning consists in selecting a goal-directed control strategy, we sought to investigate the influence of reward on feedback control. Here, we explored this question in three human reaching experiments. First, we altered the explicit reward associated with the goal target and found an overall increase in feedback gains for higher target rewards, highlighted by larger velocities, feedback responses to external loads, and background muscle activity. Then, we investigated whether the differences in target rewards across multiple goals impacted rapid motor decisions during movement. We observed idiosyncratic switching strategies dependent on both target rewards and, surprisingly, the feedback gains at perturbation onset: the more vigorous movements were less likely to switch to a new goal following perturbations. To gain further insight into a causal influence of the feedback gains on rapid motor decisions, we demonstrated that biasing the baseline activity and reflex gains by means of a background load evoked a larger proportion of target switches in the direction opposite to the background load associated with lower muscle activity. Together, our results demonstrate an impact of target reward on feedback control and highlight the competition between movement vigor and flexibility.

Background Prevention of chronic pain relies on accurate detection of at-risk patients. Screening tools have been validated mainly in (sub) acute spinal pain and the need of more generic tools is high. We assessed the validity of the French version of the short Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) in patients with a large range of pain duration and localization. Methods First, we re-analyzed data from a 6-month longitudinal study of 73 patients with (sub) acute spinal pain consulting in secondary line settings. Secondly, we performed a new 12-month longitudinal study of 542 primary care patients with (sub) acute and chronic pain in different localizations (spinal, limbs, “non-musculoskeletal”). The area under the receiver operating characteristic curve and cutoff scores were computed and compared for different subpopulations and ÖMPSQ subscores. Results Data from patients suffering from (sub) acute and chronic spinal pain consulting in both primary and secondary care settings confirmed the validity of the short French ÖMPSQ version and its subsets. In the primary care cohort, the performance of the questionnaire and its psychosocial subscore was variable but at least “fair” in most populations ((sub) acute and chronic, spinal and limb pain). Cutoff scores showed quite large variability depending on the outcome and the subpopulation considered. Conclusions These results confirm the usefulness of the short French ÖMPSQ for prediction of the evolution of (sub) acute and chronic patients with spinal and limb pain, whatever its duration. However, increasing population heterogeneity results in slightly worse predictive performance and largely variable cutoff scores. Consequently, it might be difficult to choose universal cutoff scores and other criteria, such as patients’ values and the available resources for patient management, should be taken into account.

Stratified approaches to spinal pain that address psychosocial risk factors reduce long-term disability to a moderate extent. Identifying and managing other risk factors might help improve outcomes. This systematic review of longitudinal studies aimed to evaluate possible associations between the onset of chronic spinal pain (including low back, back and neck pain) and putative modifiable lifestyle-related risk or protective factors. This systematic review of longitudinal studies published during the last 2 decades followed PRISMA guidelines. Two reviewers screened Medline, Scopus, Pedro, Cochrane Library, Psycinfo, Science Direct, PTSDpubs and Google Scholar for relevant studies. The QUIPS tool was used to assess the risk of bias. A qualitative meta-synthesis of relevant factors was performed. Of 3716 unique records, 14 studies met the inclusion criteria (10 with low risk of bias and 4 moderate risk of bias). The highest bias observed was attrition. For chronic low back pain, we found moderate evidence for the involvement of high body weight, waist circumference, and hip circumference and conflicting evidence for high body mass index (BMI), smoking, and physical activity. For chronic neck pain, we found strong evidence for high BMI in women, moderate evidence for sleep disorders in women and conflicting evidence for high BMI in men and physical activity. For chronic back pain, we found limited evidence for gardening/yard work in men and more than one adult at home. Effect sizes were small. Several modifiable lifestyle-related factors were identified. Evidence is still sparse and there is a need for more studies. PROSPERO database registration: Ref 172,112 CRD42020172112.

From the child playing with its toys to the surgeon holding its scalpel, object manipulation in everyday life is omnipresent. This skill relies on collecting information on the state of the manipulated object using our senses, with touch being of first importance. Using the information provided by touch, our central nervous system sends commands to our muscles to perform movements that take into account how slippery an object is, its shape, the characteristics of the desired movement, and more. In this thesis, we studied how finger skin deformations influence object manipulation, as touch and skin deformations are closely linked. First, we present a novel device that allows for the measurement of fingerpad skin deformations during active manipulation and present the link between the grip force and skin deformations during a simple oscillation task. Then, we show how localized fingerpad strains allow to quickly adapt the grip force to the friction when lifting objects. Finally, we show how the grip force is adjusted so that the upper bound of the amount of partial slip and finger skin deformation remain similar across friction conditions. This work contributes to the understanding of the role of touch during object manipulation and provides useful information for the design of friction sensors and somatosensory prostheses., (FSA - Sciences de l'ingénieur) -- UCL, 2022

Parkinson's disease is a severe neurodegenerative disorder that affects sensorimotor control. In particular, several gait impairments are reported, including a decrease of long-range autocorrelations in stride duration time series. This complex statistics is potentially a biomarker of the risk of falling. This paper aims at developing model-based predictions about the loss of long-range autocorrelations in the gait of Parkinsonian patients, and how these autocorrelations can be restored by an oscillator-based walking assistance. Using a Super Central Pattern Generator model coupled with an adaptive oscillator, we show that this type of assistance has the potential to improve long-range autocorrelations in time series of Parkinsonian walkers. This requires however to tune the adaptive oscillator with slow learning gains, raising challenges for porting this method to an actual device.

Background Habituation is a response decrement resulting from repeated stimuli. Reduced habituation to noxious stimuli is considered to be a proxy for central sensitization in subjects with chronic pain. Despite numerous investigations of pain habituation in relation to central sensitization, there is no consensus on the most sensitive and reliable readout, as well as analysis approach. Therefore, this study compared the usability and reliability of different readouts and habituation analysis approaches to measure pain habituation in response to repetitive heat simulation. Methods Three blocks of 20 contact heat stimuli were applied on the volar forearm of 20 healthy subjects on two separate visits. Habituation was assessed by three different readouts: pain ratings, contact heat evoked potentials (CHEPs) and heat-induced sympathetic skin responses (SSRs). In addition, two different habituation analysis approaches were used: between the three stimulation blocks (between-block) and within the first stimulation block (within-block). Results Significant between-block habituation for SSRs (p < 0.001), but not for pain ratings (p = 1.000) and CHEPs (p = 0.078) was found. There was significant within-block habituation for pain ratings (p = 0.012) and SSRs (p < 0.001), but not for CHEPs (p = 0.246). Only the between-block habituation of heat-induced SSR was reliable between the two visits (first to second block: intraclass correlation coefficient [ICC] = 0.58, p = 0.030; first to third block: ICC = 0.64, p = 0.015). Conclusion Heat-induced SSR as a measure of pain-autonomic interaction revealed the strongest pain habituation and showed the highest test–retest reliability.

BACKGROUND: SATIS-Stroke questionnaire has been translated and adapted for use in the Brazilian population, however, it is necessary to test the measurement properties in Brazilian population. OBJECTIVE: To test the reliability, agreement, concurrent validity, and diagnostic accuracy of the SATIS-Stroke. METHODS: Chronic stroke survivors were included. The calculations were made using scores in logits (Rasch Model). Reliability was tested using the intraclass correlation coefficient (ICC2,1), standard error of measurement (SEM), minimal detectable change (MDC), and Bland-Altman plots. Concurrent validity was analyzed using Spearman's correlation coefficient. For such, the correlation between SATIS-Stroke and Stroke Specific Quality of Life (SS-QOL) questionnaires was determined. Diagnostic accuracy was estimated based on the area under the receiver operating characteristic (ROC) curve with a 95% confidence interval and considering the sensitivity and specificity of SATIS-Stroke in differentiating different types of activity and participation. RESULTS: Eighty stroke survivors were analyzed. Mean age was 57.98±13.85 years and 45.2% had severe impairment. Excellent reliability was found (intra-observer ICC2,1 = 0.90; 95% CI: 0.84, 0.93; inter-observer ICC2,1 = 0.89; 95% CI: 0.83, 0.93). The Bland-Altman plot demonstrated satisfactory agreement. In the analysis of concurrent validity, a strong, positive, significant correlation was found between SATIS-Stroke and SS-QOL (rs = 0.74; p <0.001 with an r2=0.44; p=0.001). Diagnostic accuracy was satisfactory, with 80.8% sensitivity and 85.2% specificity. CONCLUSION: The Brazilian version of the SATIS-Stroke questionnaire exhibited adequate reliability, concurrent validity, and diagnostic accuracy. Therefore, this is a valid, reproducible measure for the assessment of satisfaction with regard to activities and participation following a stroke.

In locomotion tasks like walking or stair ascending, leg joints produce mechanical energy with task-specific kinematic and kinetic patterns. Consequently, locomotion assistive devices should be active and adaptive to the task being executed; and these tasks should be detected early enough for guaranteeing smooth transitions by the device controller. Wearable vision sensors can predict future tasks by detecting locomotion affordances in the environment. We implemented such a vision-based terrain detection system for flat ground, steps, and ramps, using a depth camera mounted on the user’s chest, and a machine learning classifier. A validation study was conducted with eight participants moving through indoor and outdoor paths combining a rich set of terrains, and under two clearance conditions: clear and occluded by another walker moving ahead. Our method can predict the locomotion modes up to three steps in front of the user and can estimate the geometrical features of the terrain (i.e. step height for stairs and slope inclination for ramps and grounds). Our system achieved more than 95% of accuracy for all locomotion modes in first upcoming step in clear path condition. The paper further reports how these results degrade for next steps ahead of the user, or with partial occlusion.

Background and aims: Using frequency tagging, Colon et al. (2017) found that periodic noxious heat stimuli elicits periodic modulations of the magnitude of ongoing EEG oscillations in theta, alpha and beta frequency bands. Our study aimed to assess whether these responses are specific for heat pain by comparing heat-evoked responses to the responses elicited by innocuous cold and mechanical vibrations. Methods: Twenty subjects participated to two experimental sessions, one for foot dorsum and one for volar forearm stimulation. Stimuli consisted in fifteen 200ms pulses delivered at 0.25Hz. Fourteen stimuli of each modality were delivered per session. Thermal stimuli were delivered using a contact thermode. Target temperatures were 10°C and 60°C for cold and hot stimulation, respectively. Vibrotactile stimulation (200Hz) were delivered using a round-tipped piezo-electric actuator. The EEG was recorded at 1024Hz using 66 electrodes. Hilbert transforms were used to assess the envelope of theta-, alpha- and beta-band oscillations. Frequency tagging was used to reconstruct the amplitude of the periodic response. Cluster based permutation tests were used to assess whether these amplitudes were larger than 0. Results: Periodic modulations of the theta, alpha and beta bands were observed for all modalities and limbs. For a given limb, the topographies of these modulations were similar for all modalities and modulations observed during upper limb stimulation had similar topographies to those reported by Colon et al. Conclusions: Periodic noxious heat, innocuous cold and innocuous vibrations all induce similar periodic modulations of theta, alpha and beta band oscillations

Under certain conditions, a stimulus applied at a given frequency will lead to a periodic variation of neural activity at the same frequency. Taking advantage of this periodicity, it is possible to tag this response in the EEG frequency spectrum. Frequency tagging of sustained periodic noxious heat stimuli led to the recording of phase-locked and non-phase-locked responses whose functional significance remains unclear. This study aimed at assessing whether such responses can also be recorded during the repetitive presentation of brief innocuous cold, noxious heat and vibrotactile stimuli. Comparison between the responses obtained with different stimulation modalities should inform us on the nature of the neural processes underlying these responses (modality aspecific, somatosensory, thermosensory, nociceptive). Comparison between upper and lower limb stimulation should inform us on the somatotopic organization of these responses and, therefore, on their potential sources. Based on our results, on one hand, trains of brief innocuous cold, noxious heat and vibrations can elicit phase-locked and non-phase-locked responses which appear highly similar to those evoked by sustained periodic noxious heat stimuli when frequency tagged. On the other hand, when analysed in the time domain or using time-frequency decomposition, these responses appeared highly similar to those that can be recorded following isolated brief noxious heat or tactile stimuli. These responses consisted in phase-locked activity corresponding to the vertex potential, thought to reflect modality non-specific attentional processes, and in an alpha-to-beta ERD originating in the S1/M1 area contralateral to the stimulated hand, probably reflecting non-specific somatosensory activity.

Temperature sensing is involved in many different functions, ranging from fundamental homeostatic regulation to complex inferential processes on outside world properties. Due to the technical difficulty of generating well controlled cooling stimuli, significantly less research has been conducted on cold than on heat perception. The availability of new stimulators, enabling the generation of fast and strong cold stimuli, opens new experimental possibilities. This PhD dissertation aimed to develop new techniques to probe human innocuous cold perception, use these new techniques to probe the neurophysiological mechanisms underlying human cold perception, and assess whether these new techniques could be of interest in a clinical setting. These efforts were directed more specifically in two directions: improving the psychophysical assessment of cold detection and developing stimuli and analysis techniques allowing the exploration of cold evoked activity with electroencephalography., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Pain, besides its contribution to body homeostasis, has also the function of providing information on external stimuli that can potentially harm the body. Such exteroceptive function relies on an optimally integrated multisensory representation of the body and its surrounding space, which is based on the interaction between somatic and extra-somatic stimuli occurring near the body. While the existence of such interactions between nociceptive and visual stimuli has recently been demonstrated, showing that visual stimuli outside the body can impact the perception of nociceptive stimuli and vice versa, their functional role is not clear yet. It is indeed hypothesized that one of the functions of such multisensory representations would be to optimize defensive reactions against threatening stimuli. However, the idea of this potential defensive purpose has, to date, mainly been based on a set of studies conducted in non-human primates. The aim of the present study was to investigate whether interactions between nociceptive and external visual stimuli can shape motor reactions of the stimulated limb. More specifically, we tested in 24 participants whether spinal nociceptive excitability, as measured by the spinal nociceptive withdrawal reflex (NWR) in response to noxious stimuli, can be modulated by external visual stimuli, specifically those approaching the body part on which the nociceptive stimuli are applied. NWRs were elicited by applying transcutaneous electrical stimuli in the sole of the foot of the participants. Depending on the condition, the electrical stimulus was either preceded by a dynamic visual stimulus rapidly approaching a location near the stimulated foot (NWR-visual near condition), a dynamic visual stimulus approaching a location further away from the stimulated foot (NWR-visual far condition), or was applied without any dynamic visual stimulus (NWR only condition). The electrical stimulation could be applied at one out of two possible time points of

Hand laterality judgments (HLT) are widely used to measure body representation difficulties in Complex Regional Pain Syndrome (CRPS), as well as in its rehabilitation, with the aim to activate motor imagery and restore the cortical representation of the affected limb. The potential of these tasks to elicit motor imagery is critical to their use in therapy, yet, the influence of the biomechanical constraints (BMC) on HLT reaction time, supposed to reflect motor imagery, is rarely verified. Here we investigated the influence of BMC on the perception of hand postures and movements. In a first HLT experiment, CRPS patients were significantly slower than controls in judging hand stimuli, whether or not they corresponded to their affected hand. Reaction time patterns reflecting BMC were inconclusive in CRPS and controls, questioning the validity of the task in activating motor imagery. A second experiment therefore directly investigated the influence of implicit knowledge of BMC on perceptual hand movement judgments. Participants judged the perceived path of movement between two depicted hand positions, with only one of two proposed paths that is biomechanically plausible. While the controls mostly chose the biomechanically plausible path, CRPS patients did not, indicating a disturbed perception and/or use of BMC. These findings show non-lateralized body representation impairments in CRPS, possibly related to difficulties in using correct knowledge of the body’s biomechanics. Most importantly, they indicate that it seems highly challenging to measure motor imagery and BMC indexes with the HLT, which has important implications for the rehabilitation with these tasks.

Een recent rapport van het National Institute for Health and Care Excellence vernoemt oefentherapie in groep als eerstelijnsbehandeling voor volwassen patiënten met een depressie, ook voor ernstige gevallen. Het gaat erom tegelijk de symptomen van de depressie terug te dringen, maar ook de slechtere fysieke toestand van de patiënten te verbeteren. Bij adolescenten met een depressie wordt lichaamsbeweging voorgesteld maar niet erkend als aanvullende eerstelijnsbehandeling. Bemoedigende nieuwe studies toonden nochtans een duidelijk effect tegen depressie aan bij jongeren, vooral in psychiatrische ziekenhuizen. De antidepressieve effecten van oefening in groep zouden het gevolg kunnen zijn van neurobiologische (neuroplasticiteit, ontsteking, endocriene respons…) en psychosociale (lichaamsbeeld, gevoel van eigenwaarde, gevoel van zelfredzaamheid, sociale steun…) mechanismen. Een dergelijk oefenprogramma omvat begeleiding door opgeleid personeel en zorgt voor een kader en structuur met sessies die specifiek zijn afgestemd op mensen met een depressie. De lichaamsbeweging moet aeroob zijn, van matige intensiteit met ten minste twee sessies per week bij volwassenen en drie bij adolescenten gedurende ten minste tien weken. Er moet voor worden gezorgd dat het programma aantrekkelijk is en aangepast aan de fysieke en mentale moeilijkheden van elk individu om actieve deelname aan te moedigen.

Un rapport récent du National Institute for Health and Care Excellence inclut la thérapie par l’exercice en groupe parmi les traitements de première ligne auprès des patients adultes souffrant de dépression, y compris dans les cas graves. L’intérêt est à la fois de réduire les symptômes dépressifs mais aussi d’améliorer leur santé physique plus faible. Chez l’adolescent souffrant de dépression, la pratique de l’exercice physique est suggérée mais n’est pas reconnue comme faisant partie des traitements complémentaires de première ligne. Cependant, de nouvelles études encourageantes ont montré un effet antidépresseur notable chez les jeunes, notamment en milieu hospitalier psychiatrique. Les effets antidépresseurs de l’exercice en groupe pourraient être dus à des mécanismes neurobiologiques (neuroplasticité, inflammation, réponse endocrine…) et psycho-sociaux (image de son corps, estime de soi, sentiment d’auto-efficacité, support social…). Un tel programme d’exercices physiques implique une supervision par un personnel qualifié, assurant un cadre et une structure de séances spécialement conçus pour les personnes souffrant de dépression. L’exercice doit être aérobie, d’intensité modérée avec au moins 2 séances par semaine chez l’adulte et 3 chez l’adolescent pendant au moins 10 semaines. Il faudra veiller à ce que le programme soit attrayant et adapté aux difficultés physiques et psychiques de chaque individu pour favoriser sa participation active.

Lower-limb exoskeletons are robotic devices that can provide assistance to human locomotion. Since they are expected to be used in ecological environments, their control strategy should handle different kinds of daily-life situations. Taking inspiration from the human neuromuscular system – and particularly from the so-called motor primitives – may help in adapting the type of delivered assistance to different locomotion tasks. In this work, we validated the combination of simplified primitives and a musculoskeletal model for assisting healthy subjects with a hip exoskeleton. This framework showed adaptation to the user’s gait for different slope inclinations,although its effects on the subject’s speed and their perceived effort showed no significant improvement compared to wearing the device in transparent mode.

Background and Objective: Several risk factors for the onset of CRPS have been found, but evidence for prognostic factors associated with progression of this condition remains sparse. However, detection and management of these factors are necessary to design secondary prevention strategies. The objective of this systematic review was to identify prognostic factors in adult individuals with early CRPS. Database and Data Treatment: PubMed, Embase, PsycINFO, Cochrane Library, and Scopus, published between Jan 1990 and Nov 2021. Two independent investigators selected cross-sectional and longitudinal studies looking at early (<12 weeks from onset) prognostic factors for pain, CRPS severity score, disability, return to work, or Quality of life. The Quality In Prognostic Studies (QUIPS) tool was used to assess the risk of bias. A qualitative meta-synthesis was performed. Results: Out of 4,652 different articles, six studies met inclusion criteria. We identified 21 early factors associated with poorer prognosis in type I CRPS. We found moderate evidence to support six of them: higher pain intensity, self-rated disability, anxiety, pain-related fear, being a female, and high-energy triggering event. Only two studies had an overall low risk of bias. Conclusions: This study showed an important lack of information on early prognostic factors in CRPS. Only one article investigated the link with psychological characteristics. There is a crucial need of larger studies, with well-defined population using validated measures.

Emotions have a pivotal role in our lives, and we massively express and perceive them through faces and voices. The present thesis investigates the perception and representation of emotion expressions in various contexts. In the first study, we investigated the performance of neurotypical individuals at discriminating dynamic facial and vocal emotions, with specific attention given to the time component of dynamic expressions, showing how the amount of information needed for a discriminatory decision unfolds faster in vision than audition, but always fastest in a multisensory context. In the second study we investigated the neural correlates of the perception of unimodal and multimodal expressions through functional-MRI. In this study we show how emotion information is represented in a widespread fashion throughout the regions of the face and voice processing networks. We additionally demonstrate how several of these regions not only represent their native modality, but the opposite sensory modality as well, with some doing so in a supramodal fashion, i.e. independently of the sensory modality of the input. In the third study we investigate whether visual perception is necessary for development of emotions’ discrimination through voices by testing early blind and sighted individuals. We were able to show that, although the behavioral profile is similar across the two groups for the investigated emotion categories, blindness affected the performance in specific threat-related vocal emotions., (PSYE - Sciences psychologiques et de l'éducation) -- UCL, 2022