[Disorders of the processing of spatial information in patients with right cerebral lesions and left hemi-neglect]

The aim of this research was to identify, analyze and classify disorders in behavior which occur in the use of mirrors in patients with right cerebral damage presenting left visual spatial hemiplegia. This work was based on models of visual information processing. Seven controls and eleven patients with right cerebral damage performed a test involving grasping of an object using only specular information from a conventional mirror and then from an inverted mirror. The controls grasped up all the cubes straight away. They only experienced minor difficulty with the inverted mirror, mainly in relation to lateral displacement. The patients revealed a variety of behaviors: 1) searching for and trying to seize the object in the conventional and/or inverted mirror, 2) inversion of the paralysed side (left versus right) in the inverted mirror or the appearance of a visual spatial hemiplegia, 3) modifications in the order of grasped (from right to left, from left to right, or at random), 4) directional anomalies in the horizontal plane linked (or not) with disorders in the use of the anteroposterior space. The results of this study confirm that the patients have abnormal behavior in mirror spaces. While the characteristics of this behavior shows analogies with those described in the non-recognition of objects and/or defects in the processing of visual information for localising objects in space, they can be disassociated from them, and constitute separate syndromes. Specific terminology and taxonomy for the clinical forms of mirror agnosia and specular agnosia, of mirror paralysis and specular paralysis, and of specular ataxia are proposed.