Stepping in Place While Voluntarily Turning Around Produces a Long-Lasting Posteffect Consisting in Inadvertent Turning While Stepping Eyes Closed

Figure 1

Posteffect of podokinetic stimulation and voluntary turning. In (a) the peak rotation velocity for each subject during the posteffect is plotted against the rotation velocity during the two conditioning procedures. (b) shows the mean angular velocity of the platform (Pod Stim) and of the body across subjects, during conditioning and posteffects. (c) shows the mean trace of the velocity of the body rotation (obtained by averaging the traces of all subjects) during the last minute of the podokinetic stimulation (Pod Stim, red colour, from 0 s to 60 s) and during the immediately following podokinetic after-rotation (PKAR, yellow color, 60 s to 600 s). The horizontal dashed line indicates the platform rotation velocity. (d) shows the angular velocity during the last part of voluntary turning (Vol Turn, blue, 0 s to 60 s) and the posteffect (vPKAR, green, 60 s to 600 s). The mean angular body velocity was almost null during Pod Stim but was more than 60°/s during Vol Turn (compare (c) and (d)). During the two posteffects, the mean velocities were just larger for PKAR compared to vPKAR but showed a similar initial rise and decay (the black dotted lines are the exponential fit). indicates significant difference () between mean velocities.

(a)

(b)

(c)

(d)