Fig. 5.

Relative weighting of gravity vs. to the surface as a reference for postural control during surface tilts with eyes closed. A: displacement of the body CoM during the period of surface tilts for subjects with vestibular loss (thick black lines) and control subjects (thick gray lines) is compared across tilt velocity conditions starting with the slowest, 0.5 deg/s condition (top) and progressing to the fastest, 32 deg/s condition (bottom). The CoM is shown as pitch angular rotation, anchored at the ankle joint, with backward tilts downward. B: the method used to quantify the proportion that a subject depended on gravity (Wg) vs. the support surface (Ws) as a reference for keeping the body's CoM stable during surface tilts. C: effect of surface tilt velocity on the mean (± SE) relative weighting to gravity (Wg) for subjects with vestibular loss (black line) and control subjects (gray line) in the eyes-closed condition.