A visually-driven postural after-effect

Reason, James; Wagner, Hugh; Dewhurst, D.

doi:10.1016/0001-6918(81)90065-2

Cited by 11 publications

(6 citation statements)

References 6 publications

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“…These current results are in agreement with earlier studies that also observed the same modulating effect of density on vection and postural sway [ 1 , 3 , 14 , 17 ]. With regard to postural sway, also a significant after-effect in the direction opposite to the stimulus direction was observed, which has also been found in previous studies [ 1 , 25 , 31 ]. Moreover, also this postural after-effect significantly increased with an increase in density of the rotating pattern.…”

Section: Discussionsupporting

confidence: 88%

Interaction between Depth Order and Density Affects Vection and Postural Sway

2015

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ObjectiveVection, a feeling of self-motion while being physically stationary, and postural sway can be modulated by various visual factors. Moreover, vection and postural sway are often found to be closely related when modulated by such visual factors, suggesting a common neural mechanism. One well-known visual factor is the depth order of the stimulus. The density, i.e. number of objects per unit area, is proposed to interact with the depth order in the modulation of vection and postural sway, which has only been studied to a limited degree.MethodsWe therefore exposed 17 participants to 18 different stimuli containing a stationary pattern and a pattern rotating around the naso-occipital axis. The density of both patterns was varied between 10 and 90%; the densities combined always added up to 100%. The rotating pattern occluded or was occluded by the stationary pattern, suggesting foreground or background motion, respectively. During pattern rotation participants reported vection by pressing a button, and postural sway was recorded using a force plate.ResultsParticipants always reported more vection and swayed significantly more when rotation was perceived in the background and when the rotating pattern increased in density. As hypothesized, we found that the perceived depth order interacted with pattern density. A pattern rotating in the background with a density between 60 and 80% caused significantly more vection and postural sway than when it was perceived to rotate in the foreground.ConclusionsThe findings suggest that the ratio between fore- and background pattern densities is an important factor in the interaction with the depth order, and it is not the density of rotating pattern per se. Moreover, the observation that vection and postural sway were modulated in a similar way points towards a common neural origin regulating both variables.

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Section: Discussionsupporting

confidence: 88%

Interaction between Depth Order and Density Affects Vection and Postural Sway

2015

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“…Since visual stimuli influence balance [51, 52], COP stability was assessed with subjects’ eyes either open or closed while sustaining a static footing position. The purpose was to elucidate at what speed and magnitude obese subjects deviate from a normalized COP then at what rate they return to that position while maintaining a fixed stance, and to determine if their stability is disabled when their eyes are closed.…”

Section: Discussionmentioning

confidence: 99%

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

et al. 2020

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Introduction: Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI. Subjects and Methods: Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened. Results: Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects’ eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04). Discussion and Conclusion: Importantly, these data highlight obesity’s contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

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“…Fushiki et al, 2005 (see however Guerraz and Bronstein, 2008)) and as deviations in walking trajectories have been reported with stimulation of the vestibular system (Bent et al, 2000;) it was expected that walking would be associated with subjective self-motion at least for participants that self-reported circular vection. However, as effects of vection on balance have been reported in more studies than effects on walking (Al'tman et al, 2005;Bronstein and Buckwell, 1997;Fushiki et al, 2005;Kapteyn and Bles, 1977;Reason et al, 1981;Soames and Raper, 1992;Tanaka et al, 2001), it might be the case that balance is more sensitive to self-motion illusions than walking. Indeed, concordance between participants for the walking task reached values that are being considered as small and several correlations of walking with subjective data were large, suggesting that tactile stimulation might have had a (small) effect on walking which might be statistically nonsignificant due to sample sizes being not large enough.…”

Section: Discussionmentioning

confidence: 99%

“…Fitzpatrick et al, 1994;Wardman et al, 2003). In general, visually-induced linear and circular vection induce body displacements in the same direction as that of the moving visual stimulus (Bronstein and Buckwell, 1997;Fushiki, Kobayashi, Asai, and Watanabe, 2005;Kapteyn and Bles, 1977;Reason, Wagner, and Dewhurst, 1981) and when movement of the visual stimulus stops, participants return to an upright position and there after lean in the opposite direction (Reason et al, 1981). However, participants may report vection without a balance shift, or change their balance without reporting vection (Guerraz and Bronstein, 2008) or before vection is reported (Fushiki et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Inducing circular vection with tactile stimulation encircling the waist

Tinga

Jansen²,

Smagt

et al. 2018

Acta Psychologica

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In general, moving sensory stimuli (visual and auditory) can induce illusory sensations of self-motion (i.e. vection) in the direction opposite of the sensory stimulation. The aim of the current study was to examine whether tactile stimulation encircling the waist could induce circular vection (around the body's yaw axis) and to examine whether this type of stimulation would influence participants' walking trajectory and balance. We assessed the strength and direction of perceived self-motion while vision was blocked and while either receiving tactile stimulation encircling the waist clockwise or counterclockwise or no tactile stimulation. Additionally, we assessed participants' walking trajectory and balance while receiving these different stimulations. Tactile stimulation encircling the waist was found to lead to self-reported circular vection in a subset of participants. In this subset of participants, circular vection was on average experienced in the same direction as the tactile stimulation. Additionally, perceived rotatory self-motion in participants that reported circular vection correlated with balance (i.e., sway velocity and the standard error of the mean in the medio-lateral dimension). The fact that, in this subset of participants, subjective reports of vection correlated with objective outcome measures indicates that tactile stimulation encircling the waist might indeed be able to induced circular vection.

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A visually-driven postural after-effect

Cited by 11 publications

References 6 publications

Interaction between Depth Order and Density Affects Vection and Postural Sway

Interaction between Depth Order and Density Affects Vection and Postural Sway

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

Inducing circular vection with tactile stimulation encircling the waist

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