Optical Flow with Roll Oscillations Affects Postural Control During Human Locomotion
Advisor Information
Mukul Mukherjee
Location
Dr. C.C. and Mabel L. Criss Library
Presentation Type
Poster
Start Date
6-3-2015 9:00 AM
End Date
6-3-2015 10:30 AM
Abstract
Postural control and locomotion rely on input from sensory systems. Virtual reality environments are effective for manipulating visual input. It is known that both frequency and velocity of a tilting visual scene can induce a standing postural response. However, it is unknown whether frequency or amplitude of an oscillating optical flow affects locomotion. We investigated whether medial-lateral (roll) oscillations of different frequency and amplitude combinations embedded within a natural speed-matched anterior- posterior optical flow would affect walking postural control. The dependent variable was the amount of medial-lateral drift exhibited by the C7 vertebrae reflective marker. Healthy young adults walked under ten optic flow conditions. The control condition with no oscillation was compared to nine conditions where amplitude and frequency of oscillation was manipulated. Results showed a significant main effect of frequency. This effect resulted from a reduction in excursion from 0.1 to 0.3 Hz. A significant effect of amplitude was also seen. The excursion increased significantly as the amplitude increased. We also found a significant interaction between frequency and amplitude. This was caused by a much larger increase in excursion from an amplitude of 5° to 10° at a frequency of 0.3 Hz in comparison to the other two frequencies. Therefore, amplitude of an oscillating optical flow affects medial-lateral excursion more than frequency. However, at a particular frequency threshold this effect may be reversed. Therefore, visual control of medial-lateral motion during gait depends on the amplitude and frequency of the visual feedback concurrently, but also depends on a frequency threshold.
Optical Flow with Roll Oscillations Affects Postural Control During Human Locomotion
Dr. C.C. and Mabel L. Criss Library
Postural control and locomotion rely on input from sensory systems. Virtual reality environments are effective for manipulating visual input. It is known that both frequency and velocity of a tilting visual scene can induce a standing postural response. However, it is unknown whether frequency or amplitude of an oscillating optical flow affects locomotion. We investigated whether medial-lateral (roll) oscillations of different frequency and amplitude combinations embedded within a natural speed-matched anterior- posterior optical flow would affect walking postural control. The dependent variable was the amount of medial-lateral drift exhibited by the C7 vertebrae reflective marker. Healthy young adults walked under ten optic flow conditions. The control condition with no oscillation was compared to nine conditions where amplitude and frequency of oscillation was manipulated. Results showed a significant main effect of frequency. This effect resulted from a reduction in excursion from 0.1 to 0.3 Hz. A significant effect of amplitude was also seen. The excursion increased significantly as the amplitude increased. We also found a significant interaction between frequency and amplitude. This was caused by a much larger increase in excursion from an amplitude of 5° to 10° at a frequency of 0.3 Hz in comparison to the other two frequencies. Therefore, amplitude of an oscillating optical flow affects medial-lateral excursion more than frequency. However, at a particular frequency threshold this effect may be reversed. Therefore, visual control of medial-lateral motion during gait depends on the amplitude and frequency of the visual feedback concurrently, but also depends on a frequency threshold.