[Modes of influence of vision on postural reactions associated with voluntary arm movements]

Postural changes associated with voluntary movements of the arm as observed during a positioning task, were studied on subjects standing upright on a force platform. Subjects performed the movements with either a normal visual field or without peripheral vision (tubular vision). Data analysis comprised the EMG activity of soleus and tibialis anterior and the displacement of the vertical component of the force applied to the platform. Average data of EMG indicate that the masking of the extrofoveal receptors increases the desactivation of soleus before the onset of the movement and provokes a burst of activity in the soleus 80 to 100 ms after the onset of the movement.