Specificity of the monocular crescents of the visual field in postural control

Postural reactions elicited by monocular visual stimulation in the temporal crescent of the visual field were studied in adult subjects in dynamic bal ance on a rocking platform. Circular translation of a visual scene was indu ced in the temporal crescent by the rotation of membrane prisms placed late rally to the stimulated eye. In anteroposterior balance, postural reactions are identical whichever eyes is stimulated: ventral extension of the body when the visual scene moves upwards and dorsal extension when it moves down wards. In lateral balance, postural reactions vary with the stimulated eye: extension of the right side of the body when the right eye is stimulated b y an upward displacement of the visual scene, extension of the left side wh en the left eye is stimulated. This difference, which contrasts with the si milarity of reactions elicited by the stimulation of either para-foveal fie lds, suggests that the most peripheral part of the nasal retina has a speci fic role in head and body stabilisation. (C) 1999 Academie des sciences/Edi tions scientifiques et medicales Elsevier SAS.