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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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Sample data for head position, COP, and vection responses in a typical trial. The data labeled as motion indicates the period of visual-stimulus-motion, while the data labeled as no-motion indicates the periods of no-visual-stimulus-motion. The positive vertical values indicate that head position and COP changes were in the direction of the visual-stimulus-motion. The value zero in the ordinate represents the average value during no-visual-stimulus-motion, prior to any visual-stimulus-motion.
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Figure 3: Sample data for head position, COP, and vection responses in a typical trial. The data labeled as motion indicates the period of visual-stimulus-motion, while the data labeled as no-motion indicates the periods of no-visual-stimulus-motion. The positive vertical values indicate that head position and COP changes were in the direction of the visual-stimulus-motion. The value zero in the ordinate represents the average value during no-visual-stimulus-motion, prior to any visual-stimulus-motion.

Mentions: During stimulus presentation, body sway and head position changed in the same direction as the visual stimulus rotation for all observers. That is, the observer's body inclined rightward when the stimulus rotated in a clockwise direction. Moreover, postural instability of the COP and head position changes also occurred during stimulus presentation. This is shown in Figure 3, which illustrates the typical data for COP and head position in a single trial for one observer during rightward of visual roll motion. To look at these changes of postural sway and postural instability in detail, we examined the COP and head position data in terms of average position and fluctuation of positions, and compared each of them between different periods: visual-stimulus-motion versus no-visual-stimulus-motion, and vection versus no-vection. The average positions were computed for each COP and head position as arithmetic averages across periods of the identical condition (visual-stimulus-motion or no-visual-stimulus-motion) or of the same category of perception (vection or no-vection). The fluctuations were analyzed as averaged standard deviation, or averaged-SD, that was computed for each COP and head position as arithmetic averages of standard deviations across periods of the identical condition or of the same category of perception.


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

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

Sample data for head position, COP, and vection responses in a typical trial. The data labeled as motion indicates the period of visual-stimulus-motion, while the data labeled as no-motion indicates the periods of no-visual-stimulus-motion. The positive vertical values indicate that head position and COP changes were in the direction of the visual-stimulus-motion. The value zero in the ordinate represents the average value during no-visual-stimulus-motion, prior to any visual-stimulus-motion.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Sample data for head position, COP, and vection responses in a typical trial. The data labeled as motion indicates the period of visual-stimulus-motion, while the data labeled as no-motion indicates the periods of no-visual-stimulus-motion. The positive vertical values indicate that head position and COP changes were in the direction of the visual-stimulus-motion. The value zero in the ordinate represents the average value during no-visual-stimulus-motion, prior to any visual-stimulus-motion.
Mentions: During stimulus presentation, body sway and head position changed in the same direction as the visual stimulus rotation for all observers. That is, the observer's body inclined rightward when the stimulus rotated in a clockwise direction. Moreover, postural instability of the COP and head position changes also occurred during stimulus presentation. This is shown in Figure 3, which illustrates the typical data for COP and head position in a single trial for one observer during rightward of visual roll motion. To look at these changes of postural sway and postural instability in detail, we examined the COP and head position data in terms of average position and fluctuation of positions, and compared each of them between different periods: visual-stimulus-motion versus no-visual-stimulus-motion, and vection versus no-vection. The average positions were computed for each COP and head position as arithmetic averages across periods of the identical condition (visual-stimulus-motion or no-visual-stimulus-motion) or of the same category of perception (vection or no-vection). The fluctuations were analyzed as averaged standard deviation, or averaged-SD, that was computed for each COP and head position as arithmetic averages of standard deviations across periods of the identical condition or of the same category of perception.

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