Improvement of left unilateral spatial neglect in a line extension task.

Patients with left unilateral spatial neglect following lesions that mainly involved the right parietal lobe performed a line extension task, extending a horizontal line leftward to double its original length. We examined line extension performances in the left and right hemispaces, as well as in the midline, to assess whether spatial conditions affected these performances. Whatever the severity of neglect found in the line bisection test, the line extension performances of the patients were almost accurate and comparable with those of normal controls across the three spatial conditions. The neglect patients executed movements in or toward the contralesional space as the task oriented their attention sufficiently to the left. The results suggest that the motor component, ie, directional hypokinesia, has little part in left unilateral spatial neglect due to right parietal lesions.