Performance of the human vestibuloocular reflex during locomotion.

1. The stability of gaze was measured in nine normal subjects during 30-s epochs of standing, walking in place, and running in place. The angle of gaze and head rotations in horizontal and vertical planes were measured using the magnetic search coil technique. Subjects visually fixed on a stationary object located at a distance of 100 m; thus measurements of gaze indicated the stability of images on the retina. 2. During standing, walking, or running in place, the standard deviation of the angle of gaze was less than 0.4 degrees, both horizontally and vertically. During standing and walking in place, peak gaze velocity (Gp) was less than 3.0 degrees/s. During running in place, Gp was less than 3.0 degrees/s horizontally but ranged up to 9.3 degrees/s vertically. 3. Visual acuity was measured during standing, walking, and running in place. During walking in place, five of nine subjects showed a small but significant (P = 0.03) decline in visual acuity compared with standing. During running in place, all nine subjects showed a small but significant (P = 0.002) decline in visual acuity compared with standing. 4. Stability of gaze was also measured during vigorous, voluntary head rotations in the horizontal (yaw) or vertical (pitch) planes, for 15-s epochs. Gp ranged as high as 70 degrees/s horizontally and 41 degrees/s vertically. All subjects reported illusory movement of the seen environment during these head rotations. 5. The suitability of linear systems techniques for analysis of the horizontal and vertical vestibuloocular reflex (VOR) during walking and running in place was assessed using coherence spectral analysis.(ABSTRACT TRUNCATED AT 250 WORDS)