DISSOCIATION OF SENSORY-ATTENTIONAL FROM MOTOR-INTENTIONAL NEGLECT

Objectives-Spatial neglect may result from disruption of sensory-atten tional systems that spatially allocate perceptual resources and the mo tor-intentional systems that direct exploration and action. Previous s tudies have suggested that the line bisection task is more sensitive t o sensory-attentional disorders and the cancellation task to motor-int entional disorders. A new technique was developed that allows the diss ociation of sensory-attentional and motor-intentional deficits in both tasks and thereby allows comparison of these tasks. Methods-Ten patie nts with right hemispheric injury and hemispatial neglect performed Li ne bisection and cancellation tasks while viewing stimuli on closed ci rcuit TV. Direct view of the exploring hand and the target was preclud ed; the TV monitor guided performance. The direct condition made the d irection of hand movement on the table (workspace) congruent with that on the monitor. Inverting the camera produced the indirect condition wherein the lateral movement in the workspace occurred in the opposite direction on the monitor. Results-On the cancellation task, five pati ents marked targets in the right workspace in the direct condition but the left workspace in the indirect condition, indicating sensory-atte ntional neglect. However, four other patients cancelled targets only i n the right workspace in both conditions, failing to explore the left workspace, suggesting motor-intentional neglect. A patient who perform ed ambiguously may have elements of both types of neglect. Only two ou t of five patients designated as sensory-attentional in cancellation t asks showed sensory neglect on line bisection. The other three patient s, as well as patients defined as motor-intentional by cancellation pe rformance, exhibited motor-intentional neglect on line bisection. Conc lusion-The designation of sensory-attentional versus motor-intentional neglect therefore, in part, depends on task specific demands.