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Effects of visually simulated roll motion on vection and postural stabilization.

Tanahashi S, Ujike H, Kozawa R, Ukai K - J Neuroeng Rehabil (2007)

Bottom Line: However, self-motion does not need to be consciously perceived to influence postural control.There was no clear habituation for vection and posture, and no effect of stimulus type.Our results suggested that visual stimulus motion itself affects postural control, and supported the idea that the same visual motion signal is used for vection and postural control.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science and Engineering, Waseda University, Tokyo, Japan. kg21mj23@toki.waesda.jp

ABSTRACT

Background: Visual motion often provokes vection (the induced perception of self-motion) and postural movement. Postural movement is known to increase during vection, suggesting the same visual motion signal underlies vection and postural control. However, self-motion does not need to be consciously perceived to influence postural control. Therefore, visual motion itself may affect postural control mechanisms. The purpose of the present study was to investigate the effects of visual motion and vection on postural movements during and after exposure to a visual stimulus motion.

Methods: Eighteen observers completed four experimental conditions, the order of which was counterbalanced across observers. Conditions corresponded to the four possible combinations of rotation direction of the visually simulated roll motion stimulus and the two different visual stimulus patterns. The velocity of the roll motion was held constant in all conditions at 60 deg/s. Observers assumed the standard Romberg stance, and postural movements were measured using a force platform and a head position sensor affixed to a helmet they wore. Observers pressed a button when they perceived vection. Postural responses and psychophysical parameters related to vection were analyzed.

Results: During exposure to the moving stimulus, body sway and head position of all observers moved in the same direction as the stimulus. Moreover, they deviated more during vection perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion. The postural movements also fluctuated more during vection-perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion, both in the left/right and anterior/posterior directions. There was no clear habituation for vection and posture, and no effect of stimulus type.

Conclusion: Our results suggested that visual stimulus motion itself affects postural control, and supported the idea that the same visual motion signal is used for vection and postural control. We speculated that the mechanisms underlying the processing of visual motion signals for postural control and vection perception operate using different thresholds, and that a frame of reference for body orientation perception changed along with vection perception induced further increment of postural sway.

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A model of the relationship between postural control and vection. Visual and non-visual signals are used for both vection and postural control mechanisms.
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Figure 9: A model of the relationship between postural control and vection. Visual and non-visual signals are used for both vection and postural control mechanisms.

Mentions: The result that visual-stimulus-motion inducing postural sway did not necessarily induce vection may be explained by different thresholds of processing visual motion signals for postural control as compared to vection perception mechanisms. Our results, together with that of previous study [15], suggested that both mechanisms use the same visual information. However, postural sway was even larger during visual-stimulus-motion with no-vection perception than when there was no-visual-stimulus-motion. Therefore, thresholds for postural control and vection mechanisms for processing visual information may be different. This was previously suggested by Previc and Mullen [18] in their discussion of the reasons underlying the different latencies for postural sway and vection. Based on the present results, we developed a schematic diagram illustrating the processes underlying postural control and vection. As shown in Figure 9, both visual and non-visual signals, such as vestibular and somatosensory information about body orientation, are used for postural control and vection mechanisms. The mechanisms weight the signals; if the visual signal exceeds the threshold, postural sway and vection will occur. Strictly speaking, we cannot be certain whether the weights of visual signals in the two mechanisms are different, or the thresholds are different, or both. In the model, postural instability is determined by postural sway (affected by visual and non-visual information) and directly by non-visual information.


Effects of visually simulated roll motion on vection and postural stabilization.

Tanahashi S, Ujike H, Kozawa R, Ukai K - J Neuroeng Rehabil (2007)

A model of the relationship between postural control and vection. Visual and non-visual signals are used for both vection and postural control mechanisms.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169230&req=5

Figure 9: A model of the relationship between postural control and vection. Visual and non-visual signals are used for both vection and postural control mechanisms.
Mentions: The result that visual-stimulus-motion inducing postural sway did not necessarily induce vection may be explained by different thresholds of processing visual motion signals for postural control as compared to vection perception mechanisms. Our results, together with that of previous study [15], suggested that both mechanisms use the same visual information. However, postural sway was even larger during visual-stimulus-motion with no-vection perception than when there was no-visual-stimulus-motion. Therefore, thresholds for postural control and vection mechanisms for processing visual information may be different. This was previously suggested by Previc and Mullen [18] in their discussion of the reasons underlying the different latencies for postural sway and vection. Based on the present results, we developed a schematic diagram illustrating the processes underlying postural control and vection. As shown in Figure 9, both visual and non-visual signals, such as vestibular and somatosensory information about body orientation, are used for postural control and vection mechanisms. The mechanisms weight the signals; if the visual signal exceeds the threshold, postural sway and vection will occur. Strictly speaking, we cannot be certain whether the weights of visual signals in the two mechanisms are different, or the thresholds are different, or both. In the model, postural instability is determined by postural sway (affected by visual and non-visual information) and directly by non-visual information.

Bottom Line: However, self-motion does not need to be consciously perceived to influence postural control.There was no clear habituation for vection and posture, and no effect of stimulus type.Our results suggested that visual stimulus motion itself affects postural control, and supported the idea that the same visual motion signal is used for vection and postural control.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science and Engineering, Waseda University, Tokyo, Japan. kg21mj23@toki.waesda.jp

ABSTRACT

Background: Visual motion often provokes vection (the induced perception of self-motion) and postural movement. Postural movement is known to increase during vection, suggesting the same visual motion signal underlies vection and postural control. However, self-motion does not need to be consciously perceived to influence postural control. Therefore, visual motion itself may affect postural control mechanisms. The purpose of the present study was to investigate the effects of visual motion and vection on postural movements during and after exposure to a visual stimulus motion.

Methods: Eighteen observers completed four experimental conditions, the order of which was counterbalanced across observers. Conditions corresponded to the four possible combinations of rotation direction of the visually simulated roll motion stimulus and the two different visual stimulus patterns. The velocity of the roll motion was held constant in all conditions at 60 deg/s. Observers assumed the standard Romberg stance, and postural movements were measured using a force platform and a head position sensor affixed to a helmet they wore. Observers pressed a button when they perceived vection. Postural responses and psychophysical parameters related to vection were analyzed.

Results: During exposure to the moving stimulus, body sway and head position of all observers moved in the same direction as the stimulus. Moreover, they deviated more during vection perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion. The postural movements also fluctuated more during vection-perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion, both in the left/right and anterior/posterior directions. There was no clear habituation for vection and posture, and no effect of stimulus type.

Conclusion: Our results suggested that visual stimulus motion itself affects postural control, and supported the idea that the same visual motion signal is used for vection and postural control. We speculated that the mechanisms underlying the processing of visual motion signals for postural control and vection perception operate using different thresholds, and that a frame of reference for body orientation perception changed along with vection perception induced further increment of postural sway.

Show MeSH
Related in: MedlinePlus