Left neglect for near but not far space in man

Abstract

IT has been suggested that, among the many visual areas of the human brain, there might be one set of spatial maps specialized for 'near' (peripersonal) and another for 'far' (extrapersonal) space. A distinction between 'grasping distance' and 'walking distance'¹, or between a 'reaching field' and a pointing or throwing field² has commonly been made. Evidence for such a division has been found in monkeys. Unilateral ablation of the frontal eye field (area 8) produces a more prominent inattention (or 'neglect') for objects in contralesional far space than in near space; by contrast, unilateral ablation of frontal area 6, which receives direct projections from area 7b (the rostral part of the inferior parietal lobules) results in inattention to visual stimuli limited to contralesional near space³. Despite predictions that comparable dissociations should be found in man⁴, there has been no convincing evidence. We report here such evidence in a patient with a unilateral right hemisphere stroke. Within peripersonal space, he showed severe left visuo-spatial neglect on conventional tests, including the highly sensitive task of line bisection. When line bisection was performed in extrapersonal space, neglect was abolished or attenuated.