Multisensory interactions in the automatic control of postural sway

2012 ◽  
Vol 25 (0) ◽  
pp. 77 ◽  
Author(s):  
Georg Meyer ◽  
Emma Clarke ◽  
Tony Robotham
Keyword(s):  
Postural Control ◽  
Visual Cues ◽  
Motion Tracking ◽  
Visual Motion ◽  
Postural Sway ◽  
Tracking System ◽  
Visual Display ◽  
Body Sway ◽  
Lateral Motion ◽  
Multisensory Interactions

Visual motion signals are an important source of self-motion information that are used in postural control. Bronstein and Buckwell (Exp. Brain Res. 113, 243–248, 1997) showed that postural reactions to visual motion are not rigid responses to optokinetic stimulation but specific responses appropriate for stabilising posture in natural circumstances: body sway, for instance, was abolished when participants fixated a static object in front of a laterally moving background, which in itself induced sway. We test whether haptic and auditory as well as visual fixation points reduce body sway induced by a background that either moved left/right or forward/back on a large (3 × 7 m) 3D visual display. 10 participants were asked to respond when a fixation target, whichs was presented either on a background or foreground, changed colour. Body sway was measured using a VICON motion tracking system. We tested three conditions that replicated Bronstein and Buckwell’s original study and show that body sway, induced by lateral motion of the background is abolished when participant fixate on a (virtual) foreground object. We extended their study by showing that 3D motion (looming/receding background) has a similar effect to lateral motion and to show that body sway can be effectively reduced by providing either auditory (a loudspeaker emitting a white noise) and haptic (participants lightly touch a tripod with their index finger) cues. Our findings show that postural control draws auditory and haptic as well as visual cues. The findings are relevant to the design of virtual reality systems and provide a method for objective measures of presence in virtual environments.

scholarly journals The effect of contextual cues on the encoding of motor memories

2013 ◽  
Vol 109 (10) ◽  
pp. 2632-2644 ◽  
Author(s):  
Ian S. Howard ◽  
Daniel M. Wolpert ◽  
David W. Franklin
Keyword(s):  
Visual Feedback ◽  
Visual Cues ◽  
Visual Motion ◽  
Substantial Reduction ◽  
Visual Display ◽  
Visual Object ◽  
Contextual Cues ◽  
Motion Cues ◽  
Visual Motion Cues ◽  
Display Location

Several studies have shown that sensory contextual cues can reduce the interference observed during learning of opposing force fields. However, because each study examined a small set of cues, often in a unique paradigm, the relative efficacy of different sensory contextual cues is unclear. In the present study we quantify how seven contextual cues, some investigated previously and some novel, affect the formation and recall of motor memories. Subjects made movements in a velocity-dependent curl field, with direction varying randomly from trial to trial but always associated with a unique contextual cue. Linking field direction to the cursor or background color, or to peripheral visual motion cues, did not reduce interference. In contrast, the orientation of a visual object attached to the hand cursor significantly reduced interference, albeit by a small amount. When the fields were associated with movement in different locations in the workspace, a substantial reduction in interference was observed. We tested whether this reduction in interference was due to the different locations of the visual feedback (targets and cursor) or the movements (proprioceptive). When the fields were associated only with changes in visual display location (movements always made centrally) or only with changes in the movement location (visual feedback always displayed centrally), a substantial reduction in interference was observed. These results show that although some visual cues can lead to the formation and recall of distinct representations in motor memory, changes in spatial visual and proprioceptive states of the movement are far more effective than changes in simple visual contextual cues.

IDENTIFICATION OF DYNAMIC PATTERNS OF BODY SWAY DURING QUIET STANDING: IS IT A NONLINEAR PROCESS?

2010 ◽  
Vol 20 (04) ◽  
pp. 1269-1278 ◽  
Author(s):  
HAMED GHOMASHCHI ◽  
ALI ESTEKI ◽  
JULIEN CLINTON SPROTT ◽  
ALI MOTIE NASRABADI
Keyword(s):  
Time Series ◽  
Postural Control ◽  
Correlation Dimension ◽  
Postural Sway ◽  
Convincing Evidence ◽  
Temporal Organization ◽  
Quiet Standing ◽  
Body Sway ◽  
Linear Measure ◽  
Control Mechanisms

During quiet standing, the human body continuously moves about an upright posture in an erratic fashion. Many researchers characterize postural fluctuations as a stochastic process while some others suggest chaotic dynamics for postural sway. In this study, first we examined these assumptions using principles of chaos theory in normal healthy and in patients with deteriorated postural control mechanisms. Next, we compared the ability of a nonlinear dynamics quantifier correlation dimension to that of a linear measure standard deviation to describe variability of healthy and deteriorated postural control mechanisms during quiet standing. Our findings did not provide convincing evidence for existence of low dimensional chaos within normal and abnormal sway dynamics but support the notion that postural fluctuations time series are distinguishable from these generated by a random process. The results indicated that although linear variability measures discriminated well between groups, they did not provide any information about the structure of postural fluctuations. Calculated correlation dimension as a complexity measure which describes spatio temporal organization of time series may be useful in this regard.

scholarly journals Standard reference values of the postural control in healthy young female adults in Germany: an observational study

BMJ Open ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. e026833 ◽  
Author(s):  
Daniela Ohlendorf ◽  
Charlotte Doerry ◽  
Vanessa Fisch ◽  
Sebastian Schamberger ◽  
Christina Erbe ◽  
...  
Keyword(s):  
Observational Study ◽  
Postural Control ◽  
Sagittal Plane ◽  
Postural Sway ◽  
The Body ◽  
Body Sway ◽  
Female Population ◽  
Increased Risk ◽  
Standard Values ◽  
Average Body

ObjectiveMany people of all ages suffer from vertigo due to different reasons. The comparison of patient data with standard values can highlight deteriorations or changes in postural control and thus indicate, for example, an increased risk of falling. Our aim is to measure standard values for the postural control of young healthy women.DesignObservational study.SettingInstitute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe-University Frankfurt/Main.Participants106 healthy German female subjects aged between 21 and 30 years (25±2.7 years) were measured. Their average body mass index (BMI) was 21.1±2.61 kg/m².Outcome measuresA pressure measuring platform was used to measure the weight distribution and postural sway in habitual standing. Median, tolerance range and CI were calculated.ResultsHeight, weight and BMI are comparable to the average young German female population. The load distribution between right and left foot was 49.91%:50.09%. The forefoot was less loaded than the rear foot (33.3%:66.67%). The right rear foot carried most of the body weight (34.34%). The average body sway was 9.50 mm in the frontal and 13.00 mm in the sagittal plane.ConclusionsStandard values for the postural control of the women aged 21–30 years correlate with the already collected data of healthy subjects and can therefore be described as representative. The standard values enable diagnosing and treating impaired balance.

Visual Motion Perception and Field Dependence

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 82-82
Author(s):  
B Baumberger ◽  
R Martin ◽  
M Flückiger
Keyword(s):  
Field Dependence ◽  
Large Scale ◽  
Visual Motion ◽  
Postural Sway ◽  
Body Sway ◽  
Stimulus Motion ◽  
Visual Motion Perception ◽  
Postural Responses ◽  
Field Independent ◽  
Flow Generator

The aim of this research was to throw light on the relationship between the visual field dependence, as measured by a rod-and-frame test (RFT), and the amount of recorded postural sway subsequent to a visual motion of the environment. Two groups of fifteen adult participants were split according to their results in an RFT test. They were asked to maintain an upright stance within a large-scale scenery animated by a texture flow generator. The flow consisted of either an approaching (AP) or a receding (RE) texture with respect to the observer. An ELITE system recorded antero - posterior body sway after onset and offset of stimulus motion. Both field-dependent (FD) and field-independent (FI) participants showed little reaction to AP whereas only FD participants presented a forward shift in the direction of RE at the onset. Postural responses opposite to AP and RE were marked for both groups at the offset. In conclusion we may assume an interaction between the direction specificity of the sways and a greater field dependence.

scholarly journals Rapid adaptation to Coriolis force perturbations of voluntary body sway

2019 ◽  
Vol 121 (6) ◽  
pp. 2028-2041 ◽  
Author(s):  
Avijit Bakshi ◽  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Postural Control ◽  
Coriolis Force ◽  
Sagittal Plane ◽  
Postural Sway ◽  
Force Plate ◽  
Arm Movement ◽  
Mirror Image ◽  
Body Sway ◽  
Coriolis Forces ◽  
Voluntary Sway

Studying adaptation to Coriolis perturbations of arm movements has advanced our understanding of motor control and learning. We have now applied this paradigm to two-dimensional postural sway. We measured how subjects ( n = 8) standing at the center of a fully enclosed rotating room who made voluntary anterior-posterior swaying movements adapted to the Coriolis perturbations generated by their sway. Subjects underwent four voluntary sway trials prerotation, 20 per-rotation at 10 rpm counterclockwise, and 10 postrotation. Each trial lasted 20 s, and subjects were permitted normal vision. Their voluntary sway during rotation generated Coriolis forces that initially induced rightward deviations of their forward sway paths and leftward deviations of their backward sway. Sagittal plane sway was gradually restored over per-rotation trials, and a mirror image aftereffect occurred in postrotation trials. Dual force plate data analysis showed that subjects learned to counter the Coriolis accelerations during rotation by executing a bimodal torque pattern that was asymmetric across legs and contingent on forward vs. backward movement. The experience-dependent acquisition and washout of this compensation indicate that an internal, feedforward model underlies the leg-asymmetric bimodal torque compensation, contingent on forward vs. backward movement. The learned torque asymmetry we observed for forward vs. backward sway is not consistent with parallel two-leg models of postural control. NEW & NOTEWORTHY This paper describes adaptation to Coriolis force perturbations of voluntary sway in a rotating environment. During counterclockwise rotation, sway paths are deviated clockwise, but full restoration of fore-aft sway is regained in minutes. Negative aftereffects are briefly present postrotation. Current parallel leg models of postural control cannot account for these findings, which show that postural control, like arm movement control, can adapt rapidly and completely to the Coriolis forces generated in artificial gravity environments.

Improved Postural Control after Behavioural Short Term Intervention in Patients with Psychiatric Dizziness

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
C. Best ◽  
R. Tschan ◽  
P. Dellani ◽  
N. Stieber ◽  
M. Beutel ◽  
...  
Keyword(s):  
Postural Control ◽  
Postural Sway ◽  
Vertical Plane ◽  
Behavioural Therapy ◽  
Body Sway ◽  
Control Group ◽  
Short Term ◽  
Static Posturography ◽  
Increased Activity ◽  
Conscious Control

Background:Patients with psychiatric dizziness often report subjective instability of stance and gait and fear of falls. They showed increased activity of their body sway in static posturography compared to normals (1, 2). Aim of the present study was to evaluate the efficiency of a behavioural therapy by static posturography.Methods:14 patients with psychiatric dizziness were included in the prospective study on static posturography to quantify the postural sway (sway path) during upright stance under different conditions. the psychosomatic examination comprised of standardized interviews (SCID-Interview) and a psychometric examination battery (SCL-90, VSS, VHQ). Results of static posturography were compared to those of an age-matched control group (n=23), baseline measurements were compared to the results after behavioural short term intervention.Results:At baseline patients revealed significantly lower sway-path values in the anterior-posterior and lateral planes (p< 0.001 - p=0.042) but significantly elevated values in the vertical plane (p=0.015 - p=0.042). They had to be supported more often in the examination setting to prevent falls (p< 0.001). after the short term intervention therapy a normalization of sway path values was present, especially the increased vertical sway activity was reduced (p=0.028).Conclusion:Patients with psychiatric dizziness activate significantly more anti-gravity muscles which reflects a change in postural strategy with an increased “stiffness” and a consecutively higher rate of “falls”. the patient's conscious control of stance augments coactivation of anti-gravity muscles. This typical pattern of postural control could be normalized by a short term behavioural therapy.1. Krafczyk, 1999; 2. Querner, 2000.

Effects of Long-Term Adaptation to Sway-Yoked Visual Motion and Galvanic Vestibular Stimulation on Visual and Vestibular Control of Posture

2010 ◽  
Vol 19 (6) ◽  
pp. 544-556 ◽  
Author(s):  
Michiteru Kitazaki ◽  
Takuya Kimura
Keyword(s):  
Virtual Reality ◽  
Postural Control ◽  
Visual Motion ◽  
Postural Sway ◽  
Body Movement ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Motion Platform ◽  
The Individual

Human postural control is a multimodal process involving visual and vestibular information. The aim of the present study was to measure individual differences in the contributions of vision and vestibular senses to postural control, and to investigate if the individual weights could be modulated by long-term adaptation to visual motion or galvanic vestibular stimulation (GVS). Since GVS is a less expensive technique than a motion platform and can be wearable, it is a promising virtual reality (VR) technology. We measured the postural sway of observers induced by a visual motion or GVS before and after a 7-day adaptation task. We divided participants into four groups. In visual adaptation groups, visual motions were presented to either enhance voluntary body movement (enhancing vision group) or inhibit voluntary body movement (inhibiting vision group). In GVS adaptation groups, GVS was applied to enhance voluntary body movement (enhancing GVS group) or inhibit voluntary body movement (inhibiting GVS group). The adaptation to enhancing body-movement-yoked visual motion decreased the GVS-induced postural sway at a low motion frequency. The adaptation to the enhancing GVS slightly increased the GVS-induced postural sway and decreased the visually-induced sway at a low motion frequency. The adaptation to the inhibiting GVS increased the GVS-induced postural sway and decreased the visually-induced sway at a high motion frequency. These data suggest that long-term adaptation can modify weights of vision and vestibular senses to control posture. These findings can be applied to training or rehabilitation systems of postural control and also to adaptive virtual-reality systems.

A Literature Review on Observation of the Pedestrian Step Forces

2015 ◽  
Vol 730 ◽  
pp. 43-49
Author(s):  
Liang Xu ◽  
Hai Ying Wang ◽  
Zhi Gang Song
Keyword(s):  
Motion Tracking ◽  
Visual Motion ◽  
Force Measurement ◽  
High Reliability ◽  
Tracking System ◽  
Step Length ◽  
Step Frequency ◽  
Advantages And Disadvantages ◽  
Observation Methods ◽  
Motion Characteristics

Pedestrian step forces is an important factor in the design of long-span structures. Studies have shown that walking forces is closely related to those motion characteristics including step frequency, step length, step width, walking velocity and so on. Furthermore, the motion characteristics were observed significantly influenced by walking environment which brings many uncertainties and difficulties in studying the pedestrian forces. A comparison study of the existing observation methods including the traditional direct force measurement and the latest contemporary visual motion tracking system experiment is carried out. The results show each method has its unique advantages and disadvantages. There still have no comprehensive experimental observation method to establish load model with high reliability in the structural design and vibration control. Therefore, experimental study on walking force still has a larger space for development.

scholarly journals Desktop lighting for comfortable use of a computer screen

Work ◽  
2021 ◽  
Vol 68 (s1) ◽  
pp. S209-S221
Author(s):  
Lu Han ◽  
Hechen Zhang ◽  
Zhongxia Xiang ◽  
Jinze Shang ◽  
Shabila Anjani ◽  
...  
Keyword(s):  
High Intensity ◽  
Motion Tracking ◽  
Tracking System ◽  
Computer User ◽  
Eye Tracker ◽  
Computer Screen ◽  
Task Load ◽  
Trunk Movements ◽  
Motion Tracking System ◽  
Nasa Task Load Index

BACKGROUND: The contrast between a bright computer screen and a dark ambient environment may influence comfort of the users, especially on their eyes. OBJECTIVE: The objective of this research is to identify the optimal desktop lighting for the comfortable use of the computer screen in a dark environment. METHODS: An experiment was designed where seven illumination setups were introduced for the users to perform their leisure tasks on a computer screen. Fifteen healthy subjects participated in the experiments. During each session, durations of the eye blinks, fixations and saccades of the user were recorded by an eye tracker. His/her neck and trunk movements were recorded by a motion tracking system as well. The comfort/discomfort questionnaire, localized postural discomfort questionnaire, NASA task load index and computer user questionnaire were used to record the overall comfort/discomfort, the local perceived physical discomfort, the cognitive workload, and general/eye health problems, respectively. RESULTS: Subjective and objective measurement results indicated that users felt more comfortable with high intensity warm lights using a computer screen. We also identified that the eye fixation durations, as well as the scores of two questions in the computer user questionnaire, have significant negative correlations with comfort. On the other side, the durations of blinks and the scores of three questions in the computer user questionnaire, were significantly correlated with discomfort. CONCLUSION: The warm (3000K) and high intensity (1500 lux) light reduced the visual and cognitive fatigue of the user and therefore improve the comfort of the user during the use of a computer screen.

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