OPTOKINETIC STIMULATION AFFECTS BOTH VERTICAL AND HORIZONTAL DEFICITSOF POSITION SENSE IN UNILATERAL NEGLECT

The effects of optokinetic stimulation on the disorders of position se nse in the horizontal and vertical planes were assessed in 24 patients with unilateral cerebral lesions (eight right brain-damaged patients with visuo-spatial hemineglect, eight right brain-damaged patients wit hout neglect, eight left brain-damaged patients without neglect). In n eglect patients, the position sense disorder was more severe, and affe cted by optokinetic stimulation in a direction-specific fashion. In bo th the horizontal and the vertical plane, and in both arms, stimulatio n with a direction of the movement contralateral to the side of the le sion improved the disorder, whereas stimulation with an ipsilateral di rection worsened the deficit. The suggestion is made that in patients with neglect the disorder of position sense is produced, at least in p art, by an ipsilateral distortion of an egocentric co-ordinate system, comprising both the horizontal and the vertical dimension, which may be affected by direction-specific optokinetic stimuli.