DEFICITS OF POSITION SENSE, UNILATERAL NEGLECT AND OPTOKINETIC STIMULATION

The effects of optokinetic stimulation on position sense disorders wer e investigated in a series of 30 patients with unilateral vascular les ions (10 right brain-damaged patients with visuo-spatial hemineglect, 10 right brain-damaged patients without visuo-spatial hemineglect, 10 left brain-damaged patients), and 10 control subjects. The position se nse deficit was more severe in right brain-damaged patients with negle ct, where both the contralateral and the ipsilateral arm were involved . Optokinetic stimulation was effective only in right brain-damaged pa tients with neglect: stimulation with a leftward movement (contralater al to the side of the hemispheric lesion) improved the position sense deficit, while stimulation with a rightward (ipsilateral) movement pro duced a worsening of the performance level. These findings suggest tha t in right brain-damaged patients with neglect the position sense defi cit has a nonsensory component, related to neglect, which may be affec ted by optokinetic stimulation. The role of the derangement of sensory and perceptual-egocentric representations of the body and of extraper sonal space in producing position sense disorders is discussed.