Article

Stationary visual information has a stabilizing effect on posture, whereas moving
visual information is destabilizing. We compared the influence of a stationary or
moving fixation point to the influence of stationary or moving large-field
stimulation, as well as the interaction between a fixation point and a
large-field stimulus. We recorded body sway in 20 healthy subjects who were
fixating a stationary or oscillating dot (vertical or horizontal motion, 1/3 Hz,
+/-12 degrees amplitude, distance 96 cm). In addition, a large-field random dot
pattern (extension: approximately 80 x 70 degrees) was stationary, moving or
absent. Visual fixation of a stationary dot in darkness did not reduce
antero-posterior (AP) sway compared to the situation in total darkness, but
slightly reduced lateral sway at frequencies below 0.5 Hz. In contrast, fixating
a stationary dot on a stationary large-field pattern reduced both AP and lateral
body sway at all frequencies (0.1-2 Hz). Ocular tracking of the oscillating dot
caused a peak in body sway at 1/3 Hz, i.e. the stimulus frequency, but there was
no influence of large-field stimulus at this frequency. A stationary large-field
pattern, however, reduced AP and lateral sway at frequencies between 0.1 and 2 Hz
when subjects tracked a moving dot, compared to tracking in darkness. Our results
demonstrate that a stationary large-field pattern has a stabilizing effect in all
conditions, independent of whether the eyes are fixing on a stationary target or
tracking a moving target.

Langue : ANGLAIS