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Kelly Jonathan W JW Department of Psychology, University of California, Santa Barbara, CA 93106-9660, USA. - - 2005
Two experiments investigated the role of optic flow in controlling posture. Both experiments measured postural sway in two virtual environments with different 3-D structure but the same optic flow. Observers attempted to maintain balance on one foot while viewing an object that appeared either rigid with respect to the environment ...
Ravaioli Elena E Department of Kinesiology, University of Maryland, College Park, MD 20742-2611, - - 2005
Recent models of human postural control have focused on the nonlinear properties inherent to fusing sensory information from multiple modalities. In general, these models are underconstrained, requiring additional experimental data to clarify the properties of such nonlinearities. Here we report an experiment suggesting that new or multiple mechanisms may be ...
Freitas Júnior Paulo B - - 2004
The goals of this study were to examine the visual information influence on body sway as a function of self- and object-motion perception and visual information quality. Participants that were aware (object-motion) and unaware (self-motion) of the movement of a moving room were asked to stand upright at five different ...
Rougier P - - 2004
OBJECTIVE: To assess the effects of visual feedback gain, which express the amplitudes of the displacements of the centre of pressure displayed on a computer screen. DESIGN: The controlling variable, the centre of pressure trajectories, recorded using a force platform, were decomposed into two elementary motions: (1) the horizontal displacements ...
Neilson Peter D - - 2004
A considerable body of kinematic data supports the proposal that independent visuomotor channels are involved in the control of the transport and grip components of reach and grasp. These channels are seen as having separate perceptual inputs, outputs and internal processing and are thought by some to correspond to independent ...
Gianna-Poulin Claire - - 2004
OBJECTIVE: To investigate the effect of imagining a fixed spatial reference on balance control. MATERIAL AND METHODS: Twenty-one healthy subjects were asked to remain as stable as possible while standing on a sway-referenced platform (NeuroCom Equitest posturography system). Subjects were instructed to keep their eyes open in the dark and ...
Sparto Patrick J PJ Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA 15260, USA. - - 2004
A common way for understanding sensory integration in postural control is to provide sinusoidal perturbations to the sensory systems involved in balance. However, not all subjects exhibit a response to the perturbation. Determining whether or not a response has occurred is usually done qualitatively, e.g., by visual inspection of the ...
Richerson S J - - 2004
One source of falls in the elderly may be an inability to sufficiently adjust to transient postural perturbations or slips. Identifying useful predictors of fall potential, as well as factors that affect the ability of an individual to detect a movement of the standing support surface may provide insight into ...
Gaudez C - - 2004
The purpose of this study is to determine if increasing the potential risk of slipping on support surface materials decreases postural dynamics and task performance. Seated subjects were asked to exert maximum horizontal two-handed isometric pushes as quickly as possible on a dynamometric bar. Reaction forces exerted at seat (Rxs ...
Kristeva Rumyana - - 2004
We investigated the cortico-muscular coherence in a patient with posturally induced cortically originating negative myoclonus. We recorded simultaneously 50 channels EEG and EMG from quadriceps and biceps femoris muscles of the left upper leg. Three experimental conditions were investigated with the patient in a seated position: (i) recording during rest ...
Carpenter M G - - 2004
Previous studies have shown significant effects of increased postural anxiety in healthy young individuals when standing quietly or performing voluntary postural tasks. However, little is known about the influence of anxiety on reactive postural control. The present study examined how increased postural anxiety influenced postural reactions to unexpected surface rotations ...
Jonsson Erika - - 2004
OBJECTIVE: To investigate postural steadiness during 30 s of one-leg stance in healthy young and elderly adults, by analysing the pattern of the ground reaction force variability. DESIGN: A laboratory set-up was used to analyse the variability of the ground reaction forces in relation to time as a measure of ...
Seipel Justin E - - 2004
We develop a simple hexapedal model for the dynamics of insect locomotion in the horizontal plane. Each leg is a linear spring endowed with two inputs, controlling force-free length and "hip" position, in a stereotypical feedforward pattern. These represent, in a simplified manner, the effects of neurally activated muscles in ...
Morozumi Kazunori K Hachiohji Health Cooperative Shiroyama Hospital, Tokyo, Japan. - - 2004
To investigate the influence of dentures wearing on the parameters of physical fitness, particularly on agility and balance function in elderly people. A case control study. Motohachiohjimachi, Hachiohji, Tokyo, Japan. Motor reaction time was measured in the presence and absence of dentures in the subjects who were 1) in a ...
Perret Claude - - 2004
BACKGROUND: Electromyographic (EMG) responses of erector spinae to a postural perturbation have been described and interpreted as an unloading reflex. Moreover, these responses have been found clearly and constantly abnormal in subjects presenting a progressive idiopathic scoliosis when compared with responses observed in subjects presenting a nonprogressive scoliosis or in ...
Le Bozec Serge S Laboratoire de Physiologie du Mouvement, INSERM U 483, Université de Paris-Sud, 91405 Orsay, France. - - 2004
This study was conducted under the hypothesis that voluntary movement involves a perturbation of body balance and that a counter-perturbation has to be developed to limit the perturbation effects, which is a condition necessary to perform the movement efficiently. The stabilising action is produced in body segments that constitute the ...
Jeka John - - 2004
The problem of how the nervous system fuses sensory information from multiple modalities for upright stance control remains largely unsolved. It is well established that the visual, vestibular, and somatosensory modalities provide position and rate (e.g., velocity, acceleration) information for estimation of body dynamics. However, it is unknown whether any ...
Mergner T - - 2004
Postural reflexes are replaced soon after birth by automatic reactions that allow for volition and cognition. It is still an enigma how this change in postural control is achieved. We suggest that the change involves the formation of a sensory processing level (meta level) that becomes interleaved in between the ...
Ting Lena H LH Neurological Sciences Institute, Oregon Health and Sciences University, Beaverton, OR 97006-3409, USA. - - 2004
This study sought to identify the sensory signals that encode perturbation direction rapidly enough to shape the directional tuning of the automatic postural response. We compared reactions to 16 directions of pitch and roll rotation and 16 directions of linear translation in the horizontal plane in freely standing cats. Rotations ...
Huys Raoul - - 2004
To study the acquisition of perceptual-motor skills as an instance of dynamic pattern formation, we examined the evolution of postural sway and eye and head movements in relation to changes in performance, while 13 novices practiced 3-ball cascade juggling for 9 weeks. Ball trajectories, postural sway, and eye and head ...
Balter Susan G T - - 2004
The aim of this study was to develop a standardized procedure for reproducible quantification of galvanic-induced body sway (GBS). This was a prospective experimental study conducted in a tertiary referral centre. An exploratory study was first conducted to define the galvanic vestibular stimulation (GVS) method that resulted in the best ...
Hase K K Department of Rehabilitation Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, 160-8582, Tokyo, Japan. - - 2004
Sitting down and squatting are routine activities in daily living that lower the body mass by flexing the trunk and legs, but they obviously require different motor strategies for each goal posture. The former action must transfer the supporting surface onto a seat, whereas the latter must maintain the center ...
Dimitrova Diana D Neurological Sciences Institute, Oregon Health & Science University, Portland, Oregon, - - 2004
This study tests the hypothesis that the basal ganglia are involved in optimizing postural responses for changes in perturbation direction and stance width. We compared the patterns of horizontal and vertical ground reactive forces under each leg in response to eight directions of surface translation in Parkinson's disease (PD) subjects ...
Termoz Nicolas - - 2004
The aim of this study was to assess postural response efficiency to a self-initiated perturbation using an original method based on the inverted pendulum model. Eight young subjects were asked to perform bilateral arm raising and lowering at 3 different speeds while standing on a force plate. The time necessary ...
Keshner Emily A - - 2004
Posture has traditionally been examined by isolating individual control pathways to determine their specific contributions. However, if these pathways are responsive to functional contexts, then their responses may differ when the system is receiving simultaneous inputs from multiple pathways. Thus, we may never fully understand how the central nervous system ...
Wall C C 3rd Harvard Medical School, Boston, MA, - - 2004
Body-mounted motion sensors have been shown to decrease subject sway when a tilt estimate is fed back to the user by means of an array of tactile vibrators which display estimated tilt magnitude and direction. Vestibulopathic subjects who are tested using computerized dynamic posturography show significantly reduced sway in both ...
Kuwae Yutaka Y Fujimoto Hayasuzu Hospital, Miyazaki, - - 2004
In this study, we evaluated the influence of floor materials on standing and walking in hemiplegic patients. To monitor body motion during standing and walking without any constraint, we used a measurement system that consisted of an accelerometer device, a telemeter system, and a personal computer. The posture angles in ...
Gillette Jason C - - 2004
After spinal cord injury (SCI), intact lower motor neurons can be electrically activated to produce functional muscular contractions and enhance one's capabilities beyond seated activities. Even with neuromuscular electrical stimulation (NMES), significant amounts of hand-support forces are commonly required to move from a sitting to standing position. The goal of ...
Rocchi L - - 2004
This study addresses the challenge of identifying the features of the Centre of pressure (COP) trajectory that are most sensitive to postural performance, with the aim of avoiding redundancy and allowing a straightforward interpretation of the results. Postural sway in 50 young, healthy subjects was measured by a force platform. ...
Keshner Emily A - - 2004
The purpose of this study was to identify how the postural system weights coincident yet discordant disturbances of the visual and proprioceptive/vestibular systems. Eleven healthy subjects (25-38 yrs) received either fore-aft translations of an immersive, wide field-of-view visual environment (0.1 Hz, +/- 3.7 m/sec), or anterior-posterior translations of the support ...
Li Yong Y Department of Kinesiology, FLOK, Katholieke Universiteit Leuven, Tervuursevest 101, 3001, Heverlee, - - 2004
It has often been supposed that patterns of rhythmic bimanual coordination in which homologous muscles are engaged simultaneously, are performed in a more stable manner than those in which the same muscles are activated in an alternating fashion. In order to assess the efficacy of this constraint, the present study ...
Ko Young-Gyu - - 2003
The authors investigated whether compensatory postural coordination patterns are organized according to the same dynamical principles as are nonequilibrium phase transitions. Eight participants were asked to maintain upright balance on a moving platform that was sinusoidally translated in the anterior-posterior direction and was systematically increased and decreased 0.19 Hz as ...
van der Spek Jaap H - - 2003
Paraplegic persons can stand with hip-knee-ankle-foot orthoses (HKAFO) and crutches. However, current HKAFOs restrict body movement extensively, which may impede functional upper-body movements. A more compliant body support using a more compliant orthosis or well-controlled functional electrical stimulation system may increase freedom of movement to the user, but should not ...
Fransson Per-Anders - - 2003
The objective for this study was to investigate whether the adaptation of postural control was similar during galvanic vestibular stimulation and during vibratory proprioceptive stimulation of the calf muscles. Healthy subjects were tested during erect stance with eyes open or closed. An analysis method designed to consider the adaptive adjustments ...
Park Sukyung S Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA. - - 2004
We tested whether human postural responses can be described in terms of feedback control gains, and whether these gains are scaled by the central nervous system to accommodate biomechanical constraints. A feedback control model can describe postural responses for a wide range of perturbations, but biomechanical constraints-such as on the ...
Trousselard Marion - - 2003
Without relevant visual cues, the subjective visual vertical (SVV) is biased in roll-tilted subjects toward the body axis (Aubert or A-effect). This study focused on the role of the somatosensory system with respect to the SVV and on whether somesthetic cues act through the estimated body tilt. The body cast ...
Clayton Hilary M - - 2003
OBJECTIVE: To assess the reliability of the center-of-pressure (COP) values obtained from a force platform for analysis of postural sway in horses. ANIMALS: Six 2-year-old horses that were free from lameness and neurologic disease. PROCEDURE: Horses stood stationary with all 4 hooves on a force platform; COP data were collected ...
Lamontagne Anouk - - 2003
OBJECTIVE: To compare postural adjustments to voluntary head motions during standing between stroke and healthy subjects. DESIGN: Quasi-experimental design involving two groups: stroke patients (n=8) and age-matched healthy controls (n=5). BACKGROUND: Massive sensory stimulation from the visual, vestibular and neck proprioceptive systems is conveyed during a voluntary head motion. It ...
Anand Vijay - - 2003
PURPOSE: To determine the influence of cataractous and refractive blur on postural stability and limb-load asymmetry (LLA) and to establish how postural stability changes with the spatial frequency and contrast of the visual stimulus. METHODS: Thirteen elderly subjects (mean age, 70.76 +/- 4.14 [SD] years) with no history of falls ...
Hatzitaki Vassilia V Department of Physical Education and Sport Science, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece. - - 2004
Previous studies have looked at co-processing of multiple proprioceptive inputs but few have investigated the effect of separate dynamic and tonic predominantly proprioceptive disruptions applied concurrently at the same segment. The purpose of the present study was to investigate how simultaneous ankle tendon vibration, a tonic stimulus, with a dynamic ...
Hahn Michael E - - 2003
OBJECTIVE: To determine if medio-lateral motion of the head, trunk, or pelvis demonstrates dynamic stability as well as whole-body center of mass during obstructed walking. DESIGN: Group comparison of two elderly populations using whole-body motion analysis. BACKGROUND: Detection of imbalance through analysis of center of mass motion is commonly adopted, ...
Richerson S J - - 2003
Balance control systems have usually been studied under two conditions, during quiet standing or under large postural perturbations of a magnitude that requires a postural adjustment to prevent falling. Between these two extremes lie perturbations that can be repeated and measured while not forcing adaptive strategies from the postural control ...
Latt L D - - 2003
Galvanic vestibular stimulation (GVS) applied between the mastoids during quiet standing elicits postural sway. The aim of this study was to characterize the postural sway response to continuous sinusoidal GVS across various stimulus frequencies and amplitudes. Binaural bipolar sinusoidal GVS was applied to the skin overlying the mastoid processes of ...
Pouchelle Marie - - 2003
The aim of the present experiment was to study the central control of posture and movement coordination. Subjects' task was voluntarily to raise their arms in response to a visual signal, this movement generating an unloading in which the weight of the load (0 gm, 1500 gm, 3000 gm, or ...
Mizuno Rie - - 2003
We provide an overview of the features of vestibular organs, especially of otolith organs in mutant Medaka ha. The ha fish have a dysfunction in sensing gravity due to the absence of utricular otoliths either unilaterally or bilaterally. Especially in their early developmental stages, the posture control is predominantly depend ...
Corbeil Philippe - - 2003
In this experiment, we induced muscular fatigue of ankle plantar-flexors to examine how it deteriorates the regulation of bipedal quiet upright standing. Postural stability was assessed in conditions with and without vision over 60 s period to examine not only classical postural variables (time- and frequency-domain analyses), but also structural ...
Vuillerme Nicolas - - 2003
OBJECTIVE: To investigate whether a light finger touch can compensate for the increased postural sway induced by lower-limb muscular fatigue. DESIGN: Before-after trials. SETTING: General community. PARTICIPANTS: Nine healthy university students (mean age, 23.8+/-2.6y; mean body weight, 72.7+/-6.9 kg; mean height, 177.2+/-7.5 cm). INTERVENTIONS: Participants stood with their feet together ...
Shapovalova K B - - 2003
Chronic experiments on six dogs using a model of an operant defensive reflex associated with maintenance of flexion of the hindlimb of specified amplitude were performed to compare the characteristics of the postural and movement components during the learning process. Dogs were placed standing on four tension platforms. Signals were ...
Beloozerova I N - - 2003
A deviation from the dorsal-side-up body posture in quadrupeds activates the mechanisms for postural corrections. Operation of these mechanisms was studied in the rabbit maintaining balance on a platform periodically tilted in the frontal plane. First, we characterized the kinematics and electromyographic (EMG) patterns of postural responses to tilts. It ...
Buchanan John J - - 2003
The ability to voluntarily transit from one whole-body movement to another is based on the multisensory integration of visual, vestibular, and somatosensory information. The role of functional sensory ranges and mechanical constraints on the ability to voluntarily transit between whole-body movements was studied by requiring subjects to switch from a ...
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