Grasping an object: one movement, several components.

The visuomotor transformations for producing a grasping movement imply simultaneous control of different visual mechanisms. The object size, orientation and 3D characteristics have to be encoded for the selection of the appropriate opposition space, within which the opposition forces will be applied on the object surface. These mechanisms also have to combine with those of the transport of the hand to the object location. Finally, biomechanical constraints impose categorical visuomotor decisions for positioning the opposition space according to object changes in size, orientation and spatial location. This paper examines possible interactions between the specialized structures for visuomotor transformation and the internal model that adapts prehension to its goals.