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The experimental stochastic structure of quiet stance (means and standard errors for the fixed surface condition) reported in Jeka et al. (2004). Also shown is the models' stochastic structure in quiet stance at the standard parameter values. (The stochastic structure of all four models in quiet stance at standard parameter values agree to three significant digits.)
Source publication
It is well known that the human postural control system responds to motion of the visual scene, but the implicit assumptions it makes about the visual environment and what quantities, if any, it estimates about the visual environment are unknown. This study compares the behavior of four models of the human postural control system to experimental da...
Contexts in source publication
Context 1
... restrict each model's parameter space, we assumed that γ was between 0 and 9 s −2 . We assumed c 1 = γ + ω 2 0 and c 2 = α, where ω 0 and α were two of the elements of stochastic structure reported in Jeka et al. (2004) for the fixed surface condition (Table 1). This identification is explained in Kiemel et al. (2002). ...Citations
... Experimental and simulation studies have shown that vestibular, visual, and proprioceptive information contributes to postural stabilization of the full body in upright standing (1)(2)(3)(4)(5)(6), of the unsupported lumbar spine (7,8); and the neck (9)(10)(11)(12)(13)(14)(15). In models of postural stabilization, it is typically assumed that different sensory modalities act as parallel (additive) pathways, with contributions adapted to the task and sensing uncertainty through sensory reweighting (2,16). ...
... The underlying hypothesis is that unified models of vestibular and visual sensory integration can (at least partially) explain and predict (1) postural stabilization, (2) sensory conflicts leading to motion sickness, and (3) conscious self-motion perception. 1 We evaluate this hypothesis in an analysis of head-neck stabilization in seated healthy humans, which matches conditions where sensory integration models were validated for motion sickness and self-motion perception. We adopt a biomechanical neck model presented and validated for anterior/posterior stabilization (15) and other directions including frontal impact (39). ...
Background
To counteract gravity, trunk motion, and other perturbations, the human head–neck system requires continuous muscular stabilization. In this study, we combine a musculoskeletal neck model with models of sensory integration (SI) to unravel the role of vestibular, visual, and muscle sensory cues in head–neck stabilization and relate SI conflicts and postural instability to motion sickness.
Method
A 3D multisegment neck model with 258 Hill-type muscle elements was extended with postural stabilization using SI of vestibular (semicircular and otolith) and visual (rotation rate, verticality, and yaw) cues using the multisensory observer model (MSOM) and the subjective vertical conflict model (SVC). Dynamic head–neck stabilization was studied using empirical datasets, including 6D trunk perturbations and a 4 m/s² slalom drive inducing motion sickness.
Results
Recorded head translation and rotation are well matched when using all feedback loops with MSOM or SVC or assuming perfect perception. A basic version of the model, including muscle, but omitting vestibular and visual perception, shows that muscular feedback can stabilize the neck in all conditions. However, this model predicts excessive head rotations in conditions with trunk rotation and in the slalom. Adding feedback of head rotational velocity sensed by the semicircular canals effectively reduces head rotations at mid-frequencies. Realistic head rotations at low frequencies are obtained by adding vestibular and visual feedback of head rotation based on the MSOM or SVC model or assuming perfect perception. The MSOM with full vision well captures all conditions, whereas the MSOM excluding vision well captures all conditions without vision. The SVC provides two estimates of verticality, with a vestibular estimate SVCvest, which is highly effective in controlling head verticality, and an integrated vestibular/visual estimate SVCint which can complement SVCvest in conditions with vision. As expected, in the sickening drive, SI models imprecisely estimate verticality, resulting in sensory conflict and postural instability.
Conclusion
The results support the validity of SI models in postural stabilization, where both MSOM and SVC provide credible results. The results in the sickening drive show imprecise sensory integration to enlarge head motion. This uniquely links the sensory conflict theory and the postural instability theory in motion sickness causation.
... Postural control is based on the generation of joint torques involving feedback loops (Alberts et al. 2016;Ravaioli et al. 2005;Peterka 2002;Peterka and Loughlin 2004;Kluzik et al. 2007;Cenciarini and Peterka 2006;Carver et al. 2005Carver et al. , 2006. A wide inter-individual variety of sensorimotor transformations seems to be the rule in both normal or pathological subjects, whether they involve postural responses to trunk acceleration (Vibert et al. 2001), to optokinetic stimulation (Sasaki et al. 2002), to eye closure (Lacour et al. 2016), or during the rod and frame test (Isableu et al. 2003). ...
Even for a stereotyped task, sensorimotor behavior is generally variable due to noise, redundancy, adaptability, learning or plasticity. The sources and significance of different kinds of behavioral variability have attracted considerable attention in recent years. However, the idea that part of this variability depends on unique individual strategies has been explored to a lesser extent. In particular, the notion of style recurs infrequently in the literature on sensorimotor behavior. In general use, style refers to a distinctive manner or custom of behaving oneself or of doing something, especially one that is typical of a person, group of people, place, context, or period. The application of the term to the domain of perceptual and motor phenomenology opens new perspectives on the nature of behavioral variability, perspectives that are complementary to those typically considered in the studies of sensorimotor variability. In particular, the concept of style may help toward the development of personalised physiology and medicine by providing markers of individual behaviour and response to different stimuli or treatments. Here, we cover some potential applications of the concept of perceptual-motor style to different areas of neuroscience, both in the healthy and the diseased. We prefer to be as general as possible in the types of applications we consider, even at the expense of running the risk of encompassing loosely related studies, given the relative novelty of the introduction of the term perceptual-motor style in neurosciences.
... 4) Visual perturbation: Vision constitutes another sensory channel of great importance for the neuromuscular controller. Among the RS we found 10 studies where the experiments included visual perturbations in the form of moving visual scenes [33], [34], [41], [71], [75], [77], [84], [85], [88], [90]. This makes it possible to study how the neuromuscular controller responds to motions of the visual scene, that do not correspond to the motion of the environment. ...
... where L is a matrix mapping the state vector to the controller output. Among the RS we found 16 studies [41], [55]- [57], [63], [64], [86]- [91], [95], [99]- [101] where a state feedback model was used. ...
... If the states x consist of the joint angles [99], the state feedback controller is fundamentally the same as a P controller, or a PD controller if angular velocity states also included [86]- [88], [90], [91], [95], [100], [101]. Some studies among the RS included additional state variables, such as acceleration [63], [64] (PDA controller), joint torques [55]- [57], [89] or visual scene position [41]. ...
Objective quantification of the balancing mechanisms in humans is strongly needed in health care of older people, yet is largely missing among current clinical balance assessment methods. Hence, the main goal of this literature review is to identify methods that have the potential to meet that need. We searched in the PubMed and IEEE Xplore databases using predefined criteria, screened 1064 articles, and systematically reviewed and categorized methods from 73 studies that deal with identification of neuromuscular controller models of human upright standing from empirical data. These studies were then analyzed with the particular aim to understand to what degree such methods would be useful solutions for assessing the balance of older individuals aged above 60 years. The 16 studies that included an older subject population were especially examined with this in mind. The majority of the reviewed articles focused on research questions related to the general function of human balance control rather than clinical applicability. Further efforts need to be made to adapt these methods for more accessible and mobile technologies and to ensure that the outcomes are valid for balance assessment of a general older population.
... Percepts of verticality are essential in all conditions where we have to stabilize ourselves, such as while standing or walking. Ample studies have shown that postural control (Van der Kooij et al., 1999, 2001Oie et al., 2002;Peterka, 2002;Carver et al., 2005;Happee et al., 2017) and perception of verticality (Eggert, 1998;Barnett-Cowan et al., 2005, 2011, 2013Dyde et al., 2006;Barnett-Cowan and Harris, 2008;Vingerhoets et al., 2009;Clemens et al., 2011;De Winkel et al., 2012, 2018bAlberts et al., 2016) derive from integration of sensory signals from the visual system and sensory organs responsive to gravitoinertial stimulation, and prior knowledge that "up" is usually above the head. It is generally accepted that the central nervous system constructs these percepts in a fashion that resembles calculating a vector sum (Mittelstaedt, 1983;Oman, 2003). ...
Percepts of verticality are thought to be constructed as a weighted average of multisensory inputs, but the observed weights differ considerably between studies. In the present study, we evaluate whether this can be explained by differences in how visual, somatosensory and proprioceptive cues contribute to representations of the Head In Space (HIS) and Body In Space (BIS). Participants (10) were standing on a force plate on top of a motion platform while wearing a visualization device that allowed us to artificially tilt their visual surroundings. They were presented with (in)congruent combinations of visual, platform, and head tilt, and performed Rod & Frame Test (RFT) and Subjective Postural Vertical (SPV) tasks. We also recorded postural responses to evaluate the relation between perception and balance. The perception data shows that body tilt, head tilt, and visual tilt affect the HIS and BIS in both experimental tasks. For the RFT task, visual tilt induced considerable biases (≈ 10° for 36° visual tilt) in the direction of the vertical expressed in the visual scene; for the SPV task, participants also adjusted platform tilt to correct for illusory body tilt induced by the visual stimuli, but effects were much smaller (≈ 0.25°). Likewise, postural data from the SPV task indicate participants slightly shifted their weight to counteract visual tilt (0.3° for 36° visual tilt). The data reveal a striking dissociation of visual effects between the two tasks. We find that the data can be explained well using a model where percepts of the HIS and BIS are constructed from direct signals from head and body sensors, respectively, and indirect signals based on body and head signals but corrected for perceived neck tilt. These findings show that perception of the HIS and BIS derive from the same sensory signals, but see profoundly different weighting factors. We conclude that observations of different weightings between studies likely result from querying of distinct latent constructs referenced to the body or head in space.
... Les quotients permettent quant à eux d'évaluer le degré d'utilisation des entrées sensorielles dans le contrôle postural -ce qui varie en fonction de la situation [12][13][14][15][16][17] , et de chaque personne [18][19][20][21][22][23][24][25][26][27][28][29] . Le Quotient de Romberg [30][31][32][33] consiste en un ratio entre la surface d'oscillations du CPP yeux fermés/la surface yeux ouverts. ...
Cet article est le second d'une série de trois articles portant sur la méthodologie de recherche appliquée à la podologie. Afin de pouvoir valider ses hypothèses, il est nécessaire d'utiliser des outils et tests permettant de quantifier des métriques d'intérêts. Nous abordons dans un premier temps les outils de mesure physique permettant l'analyse cinétique du pied. Les différents capteurs de forces et de pressions sont abordés avec une description de leur fonctionnement, de leur usage et leurs limites. Les outils d'analyse cinématique sont présentés afin de comprendre comment quantifier un mouvement et quel outil apporte quelle précision pour quel investissement matériel. Dans un second temps, les tests cliniques autour des symptômes et de la description morphologique sont traités. Ils permettent souvent d'aider dans les critères d'inclusion/exclusion et facilitent l'interprétation des résultats.
... Recently, extant studies systematically examined sensorimotor reweighting in children (Polastri & Barela, 2013;Rinaldi, Polastri, & Barela, 2009) and adults (Oie, Kiemel, & Jeka, 2002;Ravaioli, Oie, Kiemel, Chiari, & Jeka, 2005), and this contributed to formalizing a theoretical framework. Based on the studies, nonlinear models of postural responses to sudden amplitude changes in the visual surrounding contributed to an understanding of a few aspects of the dynamics of sensorimotor reweighting (Carver, Kiemel, & Jeka, 2006;Carver, Kiemel, van der Kooij, & Jeka, 2005;Mergner, Schweigart, Maurer, & Blumle, 2005;Van der Kooij, Jacobs, Koopman, & van der Helm, 2001). ...
The study involved investigating dyslexic children's postural control responses when visual and somatosensory cues were separately manipulated. Twenty dyslexic and 19 nondyslexic children performed a trial by standing upright inside a moving room and another by lightly touching a moving bar. Both trials lasted 240 s with the following three different stimulus characteristics: low (pretransition), high (transition), and low amplitude (posttransition). Body sway magnitude and the relationship between the movement of the room/bar surface and body sway were examined. When compared to nondyslexic children, dyslexic children oscillated with higher magnitude in the transition and posttransition under visual and somatosensory manipulation; their sway was more influenced by visual manipulation in the transition and posttransition, and they used higher applied force levels in the somatosensory modality in all conditions. The results suggest that dyslexic children could not efficiently reweight visual cues when compared to nondyslexic children. The same was not observed in the somatosensory cues when dyslexic children reduced the influence of the somatosensory stimulus. The proper use of somatosensory information was related to stronger acquired cues and higher applied forces as observed for dyslexic children. Dyslexic children experience difficulties in dynamically reweighting sensory cues although these types of difficulties are overcome when more informative sensory cues are provided.
... to correct the state estimate, which is in turn used for feedback control. When combined with optimal feedback control, these models are capable of replicating balance behaviors across a variety of mechanical and visual perturbation conditions (Kuo, 1995(Kuo, , 2005van der Kooij et al., 1999van der Kooij et al., , 2001Kiemel et al., 2002;Carver et al., 2005). These sensory integration models have proven useful in exploring different hypotheses about balance control. ...
For most individuals, balancing upright is a simple task that requires little effort. The inherent difficulties associated with standing balance are not revealed until a pathology or injury impairs its control. Fundamentally, standing upright requires us to balance our unstable whole-body load within a small base of support. Small movements of the upright body are detected by various sensory receptors, all encoding these movements through their own coordinate system with specific dynamics. The balance controller filters, processes, and integrates sensory cues of body motion to produce an error signal between predicted and actual sensory consequences of balance-related movements. Compensatory motor commands are generated in response to this error to maintain upright standing. In the present review, we first briefly describe the biomechanics and sensor dynamics of standing balance. We further review sensorimotor and perceptual approaches revealing operational principles of the balance system, along with computational approaches that explore control processes underlying upright stance. Finally, we present robotic tools that virtualize the sensory consequences, biomechanics, and/or environmental factors inherent to the standing balance task. Throughout, we emphasize works that combine sensorimotor, computational, and/or robotics approaches to highlight the task dependency, multisensory cue combinations, cortical-subcortical contributions, and internal representations underpinning balance control.
... To examine sensory reweighting, sensory stimulus amplitude and velocity have been manipulated, and changes in postural responses have been observed Oie et al., 2005) and even mathematically modeled (Carver, Kiemel, & Jeka, 2006;Carver, Kiemel, van der Kooij, & Jeka, 2005;Schöner et al., 1998). The results from these studies have indicated that the coupling between sensory information and body sway is stronger at a low amplitude of driving signals, and such coupling decreases as the stimulus amplitude is increased within a single modality (i.e., intramodality; Barela et al., 2014;Jeka, Oie, & Kiemel, 2008) and across different sensory modalities (i.e., intermodality; Polastri, Barela, Kiemel, & Jeka, 2012). ...
Postural control involves the use of sensory cues that must be properly integrated to provide specific information to accommodate continuous changes in the environment. Studies have shown several features of adaptive sensorimotor behavior, but many of the mechanisms are still unknown, such as perdurable effects. The purpose of the present study was to examine the lasting effects of visual reweighting adaptation on postural control in young adults. Seventeen young adults were exposed to a moving room situation in 3 experimental sessions that occurred on different occasions. In the first occasion, participants were exposed to seven 60-s trials, in which the room oscillated sinusoidally (0.2 Hz). The first 3 trials and last 3 trials had an amplitude of 0.6 cm and velocity of 0.6 cm/s (peak-to-peak). The fourth trial had an amplitude of 3.5 cm and velocity of 3.5 cm/s (change trial). In the second and third occasions, 1 and 7 days after the first occasion, respectively, the participants performed 3 trials with the room moving with the same parameters as the first trial in the first occasion. The results indicated that the abrupt increases in amplitude and velocity led to a less coherent and smaller magnitude of postural response to the moving room. The reduction of the induced postural response that was caused by visual manipulation lasted at least 1 week. These results suggest that adaptive changes that are caused by environmental changes are maintained for a relatively long period of time in young adults.
... De plus, le style perceptif des sujets n'est pas immuable, mais est influencé par le contexte environnemental. Des études récentes ont montré que le poids affecté à l'intégration des différents signaux est ajusté de façon dynamique et dépend de leur fiabilité, que ce soit au niveau perceptif (Ernst et Bulthoff 2004, Hillis et al. 2002, Kording et Wolpert 2004a, ou au niveau du contrôle postural (Carver et al. 2005, Dokka et al. 2010, Okumura et al. 2015 par un mécanisme dit de « repondération sensorielle ». Selon ces auteurs, l'ajustement optimal du poids des entrées sensorielles Les études d' Isableu et al. (1997Isableu et al. ( , 2003Isableu et al. ( , 2010 Les résultats ont montré, lors de l'inclinaison antérieure, en condition YO et YF, une amélioration de la stabilité par rapport à la position neutre. ...
Ce travail de thèse vise à évaluer le rôle des afférences cutanées plantaires dans le contrôle postural et oculomoteur en manipulant l’extéroception plantaire à l’aide de stimulations mécaniques plantaires fines. La 1ère étude a montré que des éléments médio-plantaires fins externes (EME) et surtout internes (EMI) améliorent la stabilité orthostatique et postériorisent le CPP de sujets jeunes et sains lors de mouvements des yeux. Ils ont aussi une action spécifique sur la vergence (pas sur les saccades) : les EMI augmentent l’amplitude phasique de divergence et diminuent la partie tonique, autrement dit agissent surtout sur la composante pré-programmée du mouvement ; alors que les EME agissent sur la convergence en augmentant son amplitude tonique, composante contrôlée sous influence de la rétroaction visuelle. Les inserts influent de manière directe sur le contrôle postural et oculomoteur par des voies spécifiques et indépendantes. La 2ème étude explique la variabilité des réponses des sujets de la 1ère. Nous avons mesuré leur degré d’utilisation des afférences extéroceptives plantaires par la méthode du Quotient Plantaire (QP = Surface CPP mousse / Surface CPP sol dur X 100). Un QP<100 suggère une Inefficience des Afférences Plantaires (IAP) : les sujets IAP ne présentent plus d’amélioration de leur stabilité ni aucune modification de la vergence avec les inserts plantaires. Nous proposons que cette situation soit non physiologique et relève d’un dysfonctionnement non douloureux latent des récepteurs plantaires, opposant les sujets IAP aux sujets ayant un QP normal. La 3ème étude a investigué les rapports entre l’utilisation des afférences plantaires et visuelles chez de jeunes adultes sains avec la méthode du QP et du Quotient du Romberg (QR). Elle mis en évidence l’existence d’une utilisation synergique des afférences visuelles et plantaires en vision de près, uniquement chez les sujets au QP normal. Les sujets IAP ont un QR plus bas que les sujets au QP normal, en vision de près et sur sol dur uniquement. Sur mousse, leur QR des sujets IAP augmente ; les yeux fermés, leur QP augmente, ce qui objective une asynergie visuo-podale. La 4ème étude, sur la même population, a montré qu’un EME bilatéral augmente l’esophorie, uniquement de loin et chez les sujets IAP. La 5ème étude a révélé l’influence de l’extéroception plantaire sur la perception de la Verticale Visuelle Subjective (VVS) sur la même population. Elle a montré une diminution de l’erreur vers la gauche de près chez les sujets au QP normal avec un EME droit, ainsi qu’une diminution de l’erreur absolue de loin chez les sujets IAP avec un EMI bilatéral. L’ensemble de ces travaux consolide au plan théorique l’importance des afférences plantaires aussi bien pour le contrôle orthostatique, le contrôle de la vergence, la perception de la VVS et l’alignement des yeux (phories). Ils démontrent que l’utilisation de ces afférences est variable selon les sujets et ont des implications cliniques pluridisciplinaires.
... In the self-motion mode, the postural control system detects changes in the visual flow field and interprets it as a self-motion, performing postural corrections as a result. The prevailing notion is that postural sway attempts to minimize a cost function such as ankle torque (Carver, Kiemel, van der Kooij, & Jeka, 2005) or retinal slip (Schöner, 1991). In most cases, the individual has no formal knowledge about the changes that take place. ...
Although the effects of cognitive tasks on postural control have been widely investigated, the influence of cognitive load on sensorimotor coupling in postural control is still being uncovered. The purpose of the present study was to investigate and compare the influence of conscious knowledge, intention, and cognitive load on the relationship between visual information and body sway in postural control in young adults. Sixteen young adults stood upright, as still as possible, inside a moving room under four experimental conditions: the participants remained still without knowing that the room was moving (dynamic condition); the participants were informed about the room’s movement (information condition) and asked to resist the room’s movement (resisted condition); the participants performed a counting task while resisting the visual influence (dual-task condition). The results showed that the influence of visual manipulation on body sway decreased when the participants were informed about the movement of the room and decreased further after they were asked to resist its movement. However, performing a dual-task led to an increase in visual influence. We conclude that intention plays a role in sensorimotor system functioning in the postural control system to alter its function if required. Nevertheless, such change demands cognitive effort, which limits attentional resources and can compromise performance in secondary tasks.
