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3. Age-Dependent Relationship between Socio-Adaptability and Motor Coordination in High Functioning Children with Autism Spectrum Disorder

Author

Kostrubiec, Viviane, Huys, Raoul, Jas, Brunhilde, and Kruck, Jeanne

Abstract

Abnormal perceptual-motor coordination is hypothesized here to be involved in social deficits of autism spectrum disorder (ASD). To test this hypothesis, high functioning children with ASD and typical controls, similar in age as well as verbal and perceptive performance, performed perceptual-motor coordination tasks and several social competence tests. Spontaneous coordination, and intentionally required in-phase and anti-phase were examined. The oscillation kinematics, as well as the accuracy and stability of spontaneous coordination were similar in both groups. In intentional coordination, ASD children produced less accurate, less stable and less complex relative phases than the control group, and in-phase and anti-phase performances that were similar in accuracy, stability, and complexity. An age-dependent relationship between socio-adaptability and coordination skills suggested these skills develop together.

Published
2018
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7. Functional Architectures for Complex Behaviors: Analysis and Modeling of Interacting Processes in a Hierarchy of Time Scales

Author

Perdikis, Dionysios, Huys, Raoul, Jirsa, Viktor, Abarbanel, Henry, Series editor, Braha, Dan, Series editor, Érdi, Péter, Series editor, Friston, Karl J, Series editor, Haken, Hermann, Series editor, Jirsa, Viktor, Series editor, Kacprzyk, Janusz, Series editor, Kaneko, Kunihiko, Series editor, Kelso, Scott, Series editor, Kirkilionis, Markus, Series editor, Kurths, Jürgen, Series editor, Menezes, Ronaldo, Series editor, Nowak, Andrzej, Series editor, Qudrat-Ullah, Hassan, Series editor, Reichl, Linda, Series editor, Schuster, Peter, Series editor, Schweitzer, Frank, Series editor, Sornette, Didier, Series editor, Thurner, Stefan, Series editor, Wunner, Günter, editor, and Pelster, Axel, editor

Published
2016
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8. Plant litter chemistry drives long-lasting changes in the catabolic capacities of soil microbial communities

Author

Bourget, Malo Y., Fanin, Nicolas, Fromin, Nathalie, Hättenschwiler, Stephan, Roumet, Catherine, Shihan, Ammar, Huys, Raoul, Sauvadet, Marie, Freschet, Grégoire T., Bourget, Malo Y., Fanin, Nicolas, Fromin, Nathalie, Hättenschwiler, Stephan, Roumet, Catherine, Shihan, Ammar, Huys, Raoul, Sauvadet, Marie, and Freschet, Grégoire T.

Abstract

Although microbial communities play an important role in explaining plant litter decomposition rates, whether and how litter chemistry may alter catabolic capacities of soil microbial communities remains poorly studied. During a 1-year litter decomposition experiment of 12 herbaceous species with contrasting litter chemistry, we examined the effect of plant litter type (roots vs. leaves) and litter chemical traits on the resulting capacity of soil microbial communities to degrade a wide range of carbon substrates of variable complexity (MicroResp™ method). Litter chemistry impacted both the total catabolic activity as well as specific catabolic capacities of microbial communities. In the early stages of litter decomposition total catabolic activity was mainly influenced by the amount of C and N in litter leachates, and litter N, P and Mg, then, later, by lignin concentrations. Some specific catabolic capacities could also be related to litter initial chemistry. Overall, litter trait effects on soil microbial communities decreased over time and the relative importance of traits shifted during the decomposition process. Our results highlight that litter chemistry is a strong driver of catabolic capacities of microbial decomposers and, while its effect fades with time, it remains substantial throughout the litter decomposition process. These long-lasting effects of litter chemistry suggest a persistent control on microbial catabolic capacities in ecosystems with recurrent litter production. Soil microbial catabolic activities were driven by broadly the same chemical traits across leaf and root litters. Synthesis. Such long-lasting effects of litter chemistry on catabolic capacities of microbial communities may represent a substantial indirect driver of the decomposition process. Disentangling the relative importance of this overlooked effect of litter chemistry on decomposition represents the next challenge. We argue that such research line should open ground-breaking

Published
2023

11. Plant litter chemistry controls coarse-textured soil carbon dynamics

Author

Huys, Raoul, Poirier, Vincent, Bourget, Malo Y., Roumet, Catherine, Hättenschwiler, Stephan, Fromin, Nathalie, Munson, Alison D., Freschet, Grégoire T., Huys, Raoul, Poirier, Vincent, Bourget, Malo Y., Roumet, Catherine, Hättenschwiler, Stephan, Fromin, Nathalie, Munson, Alison D., and Freschet, Grégoire T.

Abstract

As soils store more carbon (C) than the Earth's atmosphere and terrestrial biomass together, the balance between soil C uptake in the form of soil organic matter (SOC) and release as CO2 upon its decomposition is a critical determinant in the global C cycle regulating our planet's climate. Although plant litter is the predominant source of C fuelling both soil C build-up and losses, the issue of how litter chemistry influences this balance remains unresolved. As a contribution to solving that issue, we traced the fate of C during near-complete decomposition of 13C-labelled leaf and root litters from 12 plant species in a coarse-textured soil. We separated the soil organic carbon into mineral-associated organic matter (MAOM) and particulate organic matter (POM) pools, and investigated how 14 litter chemical traits affected novel SOC formation and native SOC mineralization (i.e. the priming effect) in these soil fractions. We observed an overall net increase in SOC due to the addition of litter, which was stronger for root than for leaf litters. The presumed stable MAOM-C pool underwent both substantial stabilization and mineralization, whereas the presumably less stable POM-C pool showed substantial stabilization and reduced mineralization. Overall, the initial increase in soil C mineralization was fully counterbalanced by a later decrease in native soil C mineralization. POM-C formation as well as MAOM-C formation and mineralization were positively related to the initial litter lignin concentration and negatively to that of the nitrogen leachates, whereas the opposite was observed for POM-C mineralization. Synthesis. Our results highlight the importance of litter chemical traits for SOC formation, and stabilization, destabilization and mineralization. In our coarse-textured soil, the amount of MAOM-C did not change despite large C fluxes through this pool. The litter chemical traits that drove these processes differed from those frequently reported for fine-textured

Published
2022

17. Performance, complexity and dynamics of force maintenance and modulation in young and older adults

Author

Knol, Hester, Huys, Raoul, Temprado, Jean-Jacques, Sleimen-Malkoun, Rita, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), and Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Adult, Male, Aging, Physiology, Science, Entropy, Musculoskeletal Physiological Phenomena, Research and Analysis Methods, Models, Biological, Young Adult, Elderly, Mathematical and Statistical Techniques, Isometric Contraction, Sine Waves, Medicine and Health Sciences, [SDV.MHEP.PHY]Life Sciences [q-bio]/Human health and pathology/Tissues and Organs [q-bio.TO], Humans, Aged, Mass Diffusivity, Analysis of Variance, Chemical Physics, [SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior, Physics, Biology and Life Sciences, [SPI.MECA.BIOM]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Biomechanics [physics.med-ph], Young Adults, Chemistry, Age Groups, Geriatrics, People and Places, Physical Sciences, Medicine, Thermodynamics, Female, Population Groupings, Physiological Processes, Organism Development, Mathematical Functions, Algorithms, Research Article, Developmental Biology
Abstract

International audience; The present study addresses how task constraints and aging influence isometric force control. We used two tasks requiring either force maintenance (straight line target force) or force modulation (sine-wave target force) around different force levels and at different modulation frequencies. Force levels were defined relative the individual maximum voluntary contraction. A group of young adults (mean age ± SD = 25 ± 3.6 years) and a group of elderly (mean age = 77 ± 6.4 years) took part in the study. Age-and task-related effects were assessed through differences in: (i) force control accuracy, (ii) time-structure of force fluctuations, and (iii) the contribution of deterministic (predictable) and stochastic (noiselike) dynamic components to the expressed behavior. Performance-wise, the elderly showed a pervasive lower accuracy and higher variability than the young participants. The analysis of fluctuations showed that the elderly produced force signals that were less complex than those of the young adults during the maintenance task, but the reverse was observed in the modulation task. Behavioral complexity results suggest a reduced adaptability to task-constraints with advanced age. Regarding the dynamics, we found comparable generating mechanisms in both age groups for both tasks and in all conditions, namely a fixed-point for force maintenance and a limit-cycle for force modulation. However, aging increased the stochasticity (noise-driven fluctuations) of force fluctuations in the cyclic force modulation, which could be related to the increased complexity found in elderly for this same task. To our knowledge this is the first time that these different perspectives to motor control are used simultaneously to characterize force control capacities. Our findings show their complementarity in revealing distinct aspects of sensorimotor adaptation to task constraints and age-related declines. Although further research is still needed to identify the physiological underpinnings, the used task and methodology are shown to have both fundamental and clinical applications.

Published
2019

18. Ebbinghaus figures that deceive the eye do not necessarily deceive the hand

Author

Knol, Hester, Huys, Raoul, Sarrazin, Jean-Christophe, Spiegler, Andreas, Jirsa, Viktor, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Département Commande des Systèmes et Dynamique du Vol, ONERA, Institut de Neurosciences des Systèmes (INS), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National de la Santé et de la Recherche Médicale (INSERM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and ONERA - The French Aerospace Lab [Salon]

Subjects
Adult, Male, Movement, [SDV]Life Sciences [q-bio], Science, Eye, Hand, Illusions, Article, [SPI]Engineering Sciences [physics], Spatio-Temporal Analysis, Touch Perception, Visual Perception, Humans, Medicine, Female, Vision, Ocular
Abstract

International audience; In support of the visual stream dissociation hypothesis, which states that distinct visual streams serve vision-for-perception and vision-for-action, visual size illusions were reported over 20 years ago to `deceive the eye but not the hand'. Ever since, inconclusive results and contradictory interpretations have accumulated. Therefore, we investigated the effects of the Ebbinghaus figure on repetitive aiming movements with distinct dynamics. Participants performed a Fitts' task in which Ebbinghaus figures served as targets. We systematically varied the three parameters which have been shown to influence the perceived size of the Ebbinghaus figure's target circle, namely the size of the target, its distance to the context circles and the size of the context circles. This paper shows that movement is significantly affected by the context size, but, in contrast to perception, not by the other two parameters. This is especially prominent in the approach phase of the movement towards the target, regardless of the dynamics. To reconcile the findings, we argue that different informational variables are used for size perception and the visual control of movements irrespective of whether certain variables induce (perceptual) illusions.

Published
2017

19. Movement speed-accuracy trade-off in Parkinson's disease

Author

Fernandez, Laure, Huys, Raoul, Issartel, Johann, Azulay, Jean-Philippe, Eusebio, Alexandre, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Dublin City University [Dublin] (DCU), Institut de Neurosciences de la Timone (INT), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Fernandez, Laure, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
speed-accuracy trade-off, [SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology, rhythmicity, [SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology, Parkinson’s disease, dopamine, goal-directed movement
Abstract

International audience; Patients with Parkinson's disease (PD) often have difficulties generating rhythmic movements, and also difficulties on movement adjustments to accuracy constraints. In the reciprocal aiming task, maintaining a high accuracy comes with the cost of diminished movement speed, whereas increasing movement speed disrupts end-point accuracy, a phenomenon well known as the speed-accuracy trade-off. The aim of this study was to examine how PD impacts speed-accuracy trade-off during rhythmic aiming movements by studying the structural kinematic movement organization and to determine the influence of dopamine replacement therapy on continuous movement speed and accuracy. Eighteen patients with advanced idiopathic Parkinson's disease performed a reciprocal aiming task, where the difficulty of the task was manipulated through target width. All patients were tested in two different sessions: ON-medication and OFF-medication state. A control group composed of healthy age-matched participants was also included in the study. The following variables were used for the analyses: Movement time, Error rate, effective target width, and Performance Index. Percentage of acceleration time and percentage of non-linearity were completed with kinematics patterns description using Rayleigh-Duffing model. Both groups traded off speed against accuracy as the constraints pertaining to the latter increased. The trade-off was more pronounced with the PD patients. Dopamine therapy allowed the PD patients to move faster, but at the cost of movement accuracy. Surprisingly, the structural kinematic organization did not differ across group nor across medication condition. These results suggest that PD patients, when involved in a reciprocal aiming task, are able to produce rhythmic movements. PD patients' overall slowing down seems to reflect a global adaptation to the disease in the absence of a structurally altered kinematic organization.

Published
2018

21. Age-dependent Relationship Between Socio-adaptability and Motor Coordination in High Functioning Children with Autism Spectrum Disorder

Author

Kostrubiec, Viviane, Huys, Raoul, Jas, Brunhilde, Kruck, Jeanne, Center for Complex Systems and Brain Sciences, Florida Atlantic University [Boca Raton], Institut de Neurosciences des Systèmes (INS), and Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
Male, Adolescent, Autism Spectrum Disorder, media_common.quotation_subject, [SHS.PSY]Humanities and Social Sciences/Psychology, Age dependent, behavioral disciplines and activities, High functioning, 050105 experimental psychology, Adaptability, Developmental psychology, Social Skills, 03 medical and health sciences, 0302 clinical medicine, Adaptation, Psychological, Developmental and Educational Psychology, medicine, Humans, 0501 psychology and cognitive sciences, Child, ComputingMilieux_MISCELLANEOUS, Motor skill, media_common, 05 social sciences, Age Factors, medicine.disease, Motor coordination, Autism spectrum disorder, Autism, Female, Social competence, Psychology, Photic Stimulation, Psychomotor Performance, 030217 neurology & neurosurgery
Abstract

Abnormal perceptual-motor coordination is hypothesized here to be involved in social deficits of autism spectrum disorder (ASD). To test this hypothesis, high functioning children with ASD and typical controls, similar in age as well as verbal and perceptive performance, performed perceptual-motor coordination tasks and several social competence tests. Spontaneous coordination, and intentionally required in-phase and anti-phase were examined. The oscillation kinematics, as well as the accuracy and stability of spontaneous coordination were similar in both groups. In intentional coordination, ASD children produced less accurate, less stable and less complex relative phases than the control group, and in-phase and anti-phase performances that were similar in accuracy, stability, and complexity. An age-dependent relationship between socio-adaptability and coordination skills suggested these skills develop together.

Published
2017
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23. Functional coordination of muscles underlying changes in behavioural dynamics

Author

Vernooij, Carlijn A., Rao, Guillaume, Perdikis, Dionysios, Huys, Raoul, Jirsa, Viktor K., Temprado, Jean-Jacques, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Institut de Neurosciences des Systèmes (INS), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National de la Santé et de la Recherche Médicale (INSERM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), and Rao, Guillaume

Subjects
Male, Behavior, Young Adult, Electromyography, Muscles, [SPI.MECA.BIOM] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Biomechanics [physics.med-ph], Humans, [SPI.MECA.BIOM]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Biomechanics [physics.med-ph], Female, Nerve Net, Article, Biomechanical Phenomena
Abstract

International audience; The dynamical systems approach addresses Bernstein's degrees of freedom problem by assuming that the neuro-musculo-skeletal system transiently assembles and dismantles its components into functional units (or synergies) to meet task demands. Strikingly, little is known from a dynamical point of view about the functioning of the muscular subsystem in this process. To investigate the interaction between the dynamical organisation at muscular and behavioural levels, we searched for specific signatures of a phase transition in muscular coordination when a transition is displayed at the behavioural level. Our results provide evidence that, during Fitts' task when behaviour switches to a different dynamical regime, muscular activation displays typical signatures of a phase transition; a reorganisation in muscular coordination patterns accompanied by a peak in the variability of muscle activation. This suggests that consistent changes occur in coordination processes across the different levels of description (i.e., behaviour and muscles). Specifically, in Fitts' task, target size acts as a control parameter that induces a destabilisation and a reorganisation of coordination patterns at different levels of the neuro-musculo-skeletal system.

Published
2016
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25. Quantifying the Ebbinghaus figure effect: target size, context size, and target-context distance determine the presence and direction of the illusion

Author

Knol, Hester, Huys, Raoul, Sarrazin, Jean-Christophe, Jirsa, Viktor, Institut de Neurosciences des Systèmes (INS), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA [Salon], ONERA, Institut National de la Santé et de la Recherche Médicale (INSERM), Conseil regional Provence-Alpes-Côte d'Azur, and the Brain Network Recovery Group through the James S. McDonnell Foundation, Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), and Université de Toulouse (UT)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
dorsal stream, ventral stream, [SCCO.NEUR]Cognitive science/Neuroscience, visual illusions, Psychology, Ebbinghaus illusion, perception, Original Research
Abstract

International audience; Citation: Knol H, Huys R, Sarrazin J-C and Jirsa VK (2015) Quantifying the Ebbinghaus figure effect: target size, context size, and target-context distance determine the presence and direction of the illusion. Over the last 20 years, visual illusions, like the Ebbinghaus figure, have become widespread to investigate functional segregation of the visual system. This segregation reveals itself, so it is claimed, in the insensitivity of movement to optical illusions. This claim, however, faces contradictory results (and interpretations) in the literature. These contradictions may be due to methodological weaknesses in, and differences across studies, some of which may hide a lack of perceptual illusion effects. Indeed, despite the long history of research with the Ebbinghaus figure, standardized configurations to predict the illusion effect are missing. Here, we present a complete geometrical description of the Ebbinghaus figure with three target sizes compatible with Fitts' task. Each trial consisted of a stimulus and an isolated probe. The probe was controlled by the participant's response through a staircase procedure. The participant was asked whether the probe or target appeared bigger. The factors target size, context size, target-context distance, and a control condition resulted in a 3 × 3 × 3 + 3 factorial design. The results indicate that the illusion magnitude, the perceptual distinctiveness, and the response time depend on the context size, distance, and especially, target size. In 33% of the factor combinations there was no illusion effect. The illusion magnitude ranged from zero to (exceptionally) 10% of the target size. The small (or absent) illusion effects on perception and its possible influence on motor tasks might have been overlooked or misinterpreted in previous studies. Our results provide a basis for the application of the Ebbinghaus figure in psychophysical and motor control studies.

Published
2015

26. Brain Dynamics of Aging: Multiscale Variability of EEG Signals at Rest and during an Auditory Oddball Task(1,2,3)

Author

Sleimen-Malkoun, Rita, Perdikis, Dionysios, Müller, Viktor, Blanc, Jean-Luc, Huys, Raoul, Temprado, Jean-Jacques, Jirsa, Viktor K., Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Institut de Neurosciences des Systèmes (INS), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Center for Lifespan Psychology (LIP), Max Planck Institute for Human Development, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
brain dynamics, [SCCO.NEUR]Cognitive science/Neuroscience, aging, Disorders of the Nervous System, multiscale entropy, EEG, New Research, brain signal variability, complexity
Abstract

Recently, the study of brain signal fluctuations is widely put forward as a promising entry point to characterize brain dynamics in health and disease. Although interesting results have been reported regarding how variability of brain activations can serve as an indicator of performance and adaptability in elderly, many uncertainties and controversies remain with regard to the comparability, reproducibility, and generality of the described findings, as well as the ensuing interpretations., The present work focused on the study of fluctuations of cortical activity across time scales in young and older healthy adults. The main objective was to offer a comprehensive characterization of the changes of brain (cortical) signal variability during aging, and to make the link with known underlying structural, neurophysiological, and functional modifications, as well as aging theories. We analyzed electroencephalogram (EEG) data of young and elderly adults, which were collected at resting state and during an auditory oddball task. We used a wide battery of metrics that typically are separately applied in the literature, and we compared them with more specific ones that address their limits. Our procedure aimed to overcome some of the methodological limitations of earlier studies and verify whether previous findings can be reproduced and extended to different experimental conditions. In both rest and task conditions, our results mainly revealed that EEG signals presented systematic age-related changes that were time-scale-dependent with regard to the structure of fluctuations (complexity) but not with regard to their magnitude. Namely, compared with young adults, the cortical fluctuations of the elderly were more complex at shorter time scales, but less complex at longer scales, although always showing a lower variance. Additionally, the elderly showed signs of spatial, as well as between, experimental conditions dedifferentiation. By integrating these so far isolated findings across time scales, metrics, and conditions, the present study offers an overview of age-related changes in the fluctuation electrocortical activity while making the link with underlying brain dynamics.

Published
2015

27. Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

Author

Huys, Raoul, Jirsa, Viktor K, Darokhan, Ziauddin, Valentiniene, Sonata, Roland, Per E, Huys, Raoul, Jirsa, Viktor K, Darokhan, Ziauddin, Valentiniene, Sonata, and Roland, Per E

Abstract

Neurons in the primary visual cortex spontaneously spike even when there are no visual stimuli. It is unknown whether the spiking evoked by visual stimuli is just a modification of the spontaneous ongoing cortical spiking dynamics or whether the spontaneous spiking state disappears and is replaced by evoked spiking. This study of laminar recordings of spontaneous spiking and visually evoked spiking of neurons in the ferret primary visual cortex shows that the spiking dynamics does not change: the spontaneous spiking as well as evoked spiking is controlled by a stable and persisting fixed point attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization is that it avoids the need for a system reorganization following visual stimulation, and impedes the transition of spontaneous spiking to evoked spiking and the propagation of spontaneous spiking from layer 4 to layers 2-3.

Published
2016

30. Evaluation of Handwriting Movement Kinematics: From an Ecological to a Magnetic Resonance Environment.

Author

Bisio, Ambra, Pedullà, Ludovico, Bonzano, Laura, Ruggeri, Piero, Brichetto, Giampaolo, Bove, Marco, Huys, Raoul, and Lange-Küttner, Chris

Subjects
OCCUPATIONAL therapy, HANDWRITING, HUMAN kinematics, MAGNETIC resonance imaging of the brain, STATISTICAL reliability
Abstract

Writing is a means of communication which requires complex motor, perceptual, and cognitive skills. If one of these abilities gets lost following traumatic events or due to neurological diseases, handwriting could deteriorate. Occupational therapy practitioners provide rehabilitation services for people with impaired handwriting. However, to determine the effectiveness of handwriting interventions no studies assessed whether the proposed treatments improved the kinematics of writing movement or had an effect at the level of the central nervous system. There is need to find new quantitative methodologies able to describe the behavioral and the neural outcomes of the rehabilitative interventions for handwriting. In the present study we proposed a combined approach that allowed evaluating the kinematic parameters of handwriting movements, acquired by means of a magnetic resonance-compatible tablet, and their neural correlates obtained simultaneously from a functional magnetic resonance imaging examination. Results showed that the system was reliable in term of reproducibility of the kinematic data during a test/re-test procedure. Further, despite the modifications with respect to an ecological writing movement condition, the kinematic parameters acquired inside the MR-environment were descriptive of individuals' movement features. At last, the imaging protocol succeeded to show the activation of the cerebral regions associated with the production of writing movement in healthy people. From these findings, this methodology seems to be promising to evaluate the handwriting movement deficits and the potential alterations in the neural activity in those individuals who have handwriting difficulties. Finally, it would provide a mean to quantitatively assess the effect of a rehabilitative treatment. [ABSTRACT FROM AUTHOR]

Published
2016
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31. Cortical sensorimotor activity in the execution and suppression of discrete and rhythmic movements

Author

Jean-Christophe Buisson, Mario Hervault, Pier-Giorgio Zanone, Raoul Huys, Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Argumentation, Décision, Raisonnement, Incertitude et Apprentissage (IRIT-ADRIA), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Centre de recherche cerveau et cognition (CERCO UMR5549), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Toulouse Mind & Brain Institut (TMBI), Université Toulouse Capitole (UT Capitole), Université Fédérale Toulouse Midi-Pyrénées-Toulouse Mind & Brain Institut (TMBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse Capitole (UT Capitole), and Huys, Raoul

Subjects
Adult, Male, [INFO.INFO-AI] Computer Science [cs]/Artificial Intelligence [cs.AI], Brain activity and meditation, Science, media_common.quotation_subject, Movement, Sensory system, Cognitive neuroscience, Electroencephalography, Somatosensory system, 050105 experimental psychology, Article, [INFO.INFO-AI]Computer Science [cs]/Artificial Intelligence [cs.AI], 03 medical and health sciences, [SCCO]Cognitive science, 0302 clinical medicine, Rhythm, Motor control, Perception, medicine, Humans, Psychology, 0501 psychology and cognitive sciences, media_common, Cued speech, Multidisciplinary, Lateralized readiness potential, medicine.diagnostic_test, 05 social sciences, [SCCO] Cognitive science, Medicine, Female, Sensorimotor Cortex, Beta Rhythm, Neuroscience, 030217 neurology & neurosurgery
Abstract

Although the engagement of sensorimotor cortices in movement is well documented, the functional relevance of brain activity patterns remains ambiguous. Especially, the cortical engagement specific to the pre-, within-, and post-movement periods is poorly understood. The present study addressed this issue by examining sensorimotor EEG activity during the performance as well as STOP-signal cued suppression of movements pertaining to two distinct classes, namely, discrete vs. ongoing rhythmic movements. Our findings indicate that the lateralized readiness potential (LRP), which is classically used as a marker of pre-movement processing, indexes multiple pre- and in- movement-related brain dynamics in a movement-class dependent fashion. In- and post-movement event-related (de)synchronization (ERD/ERS) observed in the Mu (8–13 Hz) and Beta (15–30 Hz) frequency ranges were associated with estimated brain sources in both motor and somatosensory cortical areas. Notwithstanding, Beta ERS occurred earlier following cancelled than actually performed movements. In contrast, Mu power did not vary. Whereas Beta power may reflect the evaluation of the sensory predicted outcome, Mu power might engage in linking perception to action. Additionally, the rhythmic movement forced stop (only) showed a post-movement Mu/Beta rebound, which might reflect an active "clearing-out" of the motor plan and its feedback-based online control. Overall, the present study supports the notion that sensorimotor EEG modulations are key markers to investigate control or executive processes, here initiation and inhibition, which are exerted when performing distinct movement classes.

Published
2021

32. To start or stop an action depends on which movement we perform: An appraisal of the horse–race model

Author

Perrine Siguier, Mario Hervault, Jean-Christophe Buisson, Pier-Giorgio Zanone, Raoul Huys, Mathilde Francheteau, Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Argumentation, Décision, Raisonnement, Incertitude et Apprentissage (IRIT-ADRIA), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Huys, Raoul, Centre de recherche cerveau et cognition (CERCO UMR5549), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Toulouse Mind & Brain Institut (TMBI), Université Toulouse Capitole (UT Capitole), Université Fédérale Toulouse Midi-Pyrénées-Toulouse Mind & Brain Institut (TMBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse Capitole (UT Capitole)

Subjects
Movement, Experimental and Cognitive Psychology, Stop signal, Stimulus (physiology), [INFO] Computer Science [cs], 050105 experimental psychology, Fingers, Executive functions, 03 medical and health sciences, 0302 clinical medicine, Cognition, Arts and Humanities (miscellaneous), Motor control, Developmental and Educational Psychology, Animals, Humans, Psychology, 0501 psychology and cognitive sciences, [INFO]Computer Science [cs], Horses, Latency (engineering), Inhibitory control, Adaptive behavior, Reaction time, Modality (human–computer interaction), 05 social sciences, Response type, General Medicine, BF1-990, Inhibition, Psychological, Action (philosophy), [SCCO.PSYC] Cognitive science/Psychology, [SCCO.PSYC]Cognitive science/Psychology, 030217 neurology & neurosurgery, Psychomotor Performance, Cognitive psychology
Abstract

International audience; In order to gauge the executive processes underlying adaptive behavior, a central criterion in psychology is the extent to which experimental findings generalize across response types. The latency of two major acts of control, action initiation and inhibition, was evaluated using a stop-signal paradigm with two response types, involving either a finger key-pressing or a wrist pen-swiping response. In both conditions, 40 participants were instructed to respond quickly to a GO stimulus but to cancel their responses when a STOP signal was presented, which occurred randomly in 25% of the trials. Taken together, analyses of reaction times and of inhibition probability functions indicated that action initiation generalized across the two response types. In contrast, the finger key-pressing and the wrist pen-swiping responses involved independent inhibition processes. These results challenge a strictly top-down view for some acts of control by showing an interaction between the executive and motor levels in terms of response modality specificity.

Published
2021

33. Multiple Brain Sources Are Differentially Engaged in the Inhibition of Distinct Action Types

Author

Raoul Huys, Pier-Giorgio Zanone, Jean-Christophe Buisson, Mario Hervault, Huys, Raoul, Centre de recherche cerveau et cognition (CERCO UMR5549), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Toulouse Mind & Brain Institut (TMBI), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Argumentation, Décision, Raisonnement, Incertitude et Apprentissage (IRIT-ADRIA), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse Capitole (UT Capitole), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Toulouse Mind & Brain Institut (TMBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse Capitole (UT Capitole), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse 1 Capitole (UT1), and Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse 1 Capitole (UT1)

Subjects
Brain network, Cingulate cortex, Brain Mapping, Cognitive Neuroscience, [SCCO.NEUR]Cognitive science/Neuroscience, 05 social sciences, [SCCO.NEUR] Cognitive science/Neuroscience, Motor Cortex, Brain, Electroencephalography, Inhibitory postsynaptic potential, Discrete action, Theta power, 050105 experimental psychology, Inhibition, Psychological, 03 medical and health sciences, 0302 clinical medicine, Rhythm, Eeg data, Action (philosophy), Humans, 0501 psychology and cognitive sciences, Psychology, Neuroscience, 030217 neurology & neurosurgery
Abstract

Most studies contributing to identify the brain network for inhibitory control have investigated the cancelation of prepared–discrete actions, thus focusing on an isolated and short-lived chunk of human behavior. Aborting ongoing–continuous actions is an equally crucial ability but remains little explored. Although discrete and ongoing–continuous rhythmic actions are associated with partially overlapping yet largely distinct brain activations, it is unknown whether the inhibitory network operates similarly in both situations. Thus, distinguishing between action types constitutes a powerful means to investigate whether inhibition is a generic function. We, therefore, used independent component analysis (ICA) of EEG data and show that canceling a discrete action and aborting a rhythmic action rely on independent brain components. The ICA showed that a delta/theta power increase generically indexed inhibitory activity, whereas N2 and P3 ERP waves did so in an action-specific fashion. The action-specific components were generated by partially distinct brain sources, which indicates that the inhibitory network is engaged differently when canceling a prepared–discrete action versus aborting an ongoing–continuous action. In particular, increased activity was estimated in precentral gyri and posterior parts of the cingulate cortex for action canceling, whereas an enhanced activity was found in more frontal gyri and anterior parts of the cingulate cortex for action aborting. Overall, the present findings support the idea that inhibitory control is differentially implemented according to the type of action to revise.

Published
2021

34. Performance, complexity and dynamics of force maintenance and modulation in young and older adults.

Author

Knol H, Huys R, Temprado JJ, and Sleimen-Malkoun R

Subjects
Adult, Aged, Algorithms, Analysis of Variance, Female, Humans, Male, Models, Biological, Young Adult, Isometric Contraction, Musculoskeletal Physiological Phenomena
Abstract

The present study addresses how task constraints and aging influence isometric force control. We used two tasks requiring either force maintenance (straight line target force) or force modulation (sine-wave target force) around different force levels and at different modulation frequencies. Force levels were defined relative the individual maximum voluntary contraction. A group of young adults (mean age ± SD = 25 ± 3.6 years) and a group of elderly (mean age = 77 ± 6.4 years) took part in the study. Age- and task-related effects were assessed through differences in: (i) force control accuracy, (ii) time-structure of force fluctuations, and (iii) the contribution of deterministic (predictable) and stochastic (noise-like) dynamic components to the expressed behavior. Performance-wise, the elderly showed a pervasive lower accuracy and higher variability than the young participants. The analysis of fluctuations showed that the elderly produced force signals that were less complex than those of the young adults during the maintenance task, but the reverse was observed in the modulation task. Behavioral complexity results suggest a reduced adaptability to task-constraints with advanced age. Regarding the dynamics, we found comparable generating mechanisms in both age groups for both tasks and in all conditions, namely a fixed-point for force maintenance and a limit-cycle for force modulation. However, aging increased the stochasticity (noise-driven fluctuations) of force fluctuations in the cyclic force modulation, which could be related to the increased complexity found in elderly for this same task. To our knowledge this is the first time that these different perspectives to motor control are used simultaneously to characterize force control capacities. Our findings show their complementarity in revealing distinct aspects of sensorimotor adaptation to task constraints and age-related declines. Although further research is still needed to identify the physiological underpinnings, the used task and methodology are shown to have both fundamental and clinical applications., Competing Interests: The authors have declared that no competing interests exist.

Published
2019
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35. Movement Speed-Accuracy Trade-Off in Parkinson's Disease.

Author

Fernandez L, Huys R, Issartel J, Azulay JP, and Eusebio A

Abstract

Patients with Parkinson's disease (PD) often have difficulties generating rhythmic movements, and also difficulties on movement adjustments to accuracy constraints. In the reciprocal aiming task, maintaining a high accuracy comes with the cost of diminished movement speed, whereas increasing movement speed disrupts end-point accuracy, a phenomenon well known as the speed-accuracy trade-off. The aim of this study was to examine how PD impacts speed-accuracy trade-off during rhythmic aiming movements by studying the structural kinematic movement organization and to determine the influence of dopamine replacement therapy on continuous movement speed and accuracy. Eighteen patients with advanced idiopathic Parkinson's disease performed a reciprocal aiming task, where the difficulty of the task was manipulated through target width. All patients were tested in two different sessions: ON-medication and OFF-medication state. A control group composed of healthy age-matched participants was also included in the study. The following variables were used for the analyses: Movement time, Error rate, effective target width, and Performance Index. Percentage of acceleration time and percentage of non-linearity were completed with kinematics patterns description using Rayleigh-Duffing model. Both groups traded off speed against accuracy as the constraints pertaining to the latter increased. The trade-off was more pronounced with the PD patients. Dopamine therapy allowed the PD patients to move faster, but at the cost of movement accuracy. Surprisingly, the structural kinematic organization did not differ across group nor across medication condition. These results suggest that PD patients, when involved in a reciprocal aiming task, are able to produce rhythmic movements. PD patients' overall slowing down seems to reflect a global adaptation to the disease in the absence of a structurally altered kinematic organization.

Published
2018
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36. Brain Dynamics of Aging: Multiscale Variability of EEG Signals at Rest and during an Auditory Oddball Task

Author

Sleimen-Malkoun R, Perdikis D, Müller V, Blanc JL, Huys R, Temprado JJ, and Jirsa VK

Abstract

The present work focused on the study of fluctuations of cortical activity across time scales in young and older healthy adults. The main objective was to offer a comprehensive characterization of the changes of brain (cortical) signal variability during aging, and to make the link with known underlying structural, neurophysiological, and functional modifications, as well as aging theories. We analyzed electroencephalogram (EEG) data of young and elderly adults, which were collected at resting state and during an auditory oddball task. We used a wide battery of metrics that typically are separately applied in the literature, and we compared them with more specific ones that address their limits. Our procedure aimed to overcome some of the methodological limitations of earlier studies and verify whether previous findings can be reproduced and extended to different experimental conditions. In both rest and task conditions, our results mainly revealed that EEG signals presented systematic age-related changes that were time-scale-dependent with regard to the structure of fluctuations (complexity) but not with regard to their magnitude. Namely, compared with young adults, the cortical fluctuations of the elderly were more complex at shorter time scales, but less complex at longer scales, although always showing a lower variance. Additionally, the elderly showed signs of spatial, as well as between, experimental conditions dedifferentiation. By integrating these so far isolated findings across time scales, metrics, and conditions, the present study offers an overview of age-related changes in the fluctuation electrocortical activity while making the link with underlying brain dynamics.

Published
2015
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