A Modern Version of a Classic: Combining the Cross Copy Task with a Computerized Tablet Reveals Subtle Motoric Deficits in Hemispatial Neglect

摘要

Figure-copying tasks capture fundamental aspects of visuomotor cognition, which include motor planning/execution, spatial attention, and visuomotor feedback processing. Correspondingly, these tasks are widely used for neuropsychological assessment of visuomotor and visuospatial abilities such as identifying deficits in patients with hemispatial neglect. However, copying assessments are typically scored in a coarse manner, lacking real-time detail. To improve these methods, we had participants draw a symmetrical 12-segment Greek cross on a piece of paper (Reitan, 1963) placed on a computerized tablet, allowing us to measure the precise length, velocity, and initiation time of each line segment. Participants drew the cross in both clockwise and counter-clockwise directions as well as with and without ink (visible and invisible conditions). This allowed the separate analysis of leftward or rightward motion in various positions as well as how participants use visual feedback. To validate this task, we compared performance of patients suffering from hemispatial neglect with a group of healthy age-matched controls. Although many neglect patients scored in the normal range using traditional scoring methods based on the appearance of the overall figure, details of the movements were significantly different from healthy controls. In particular, left-hemifield neglect patients had slower velocities when moving rightward on the left side of the figure compared to movements on the right. Additionally, several neglect patients demonstrated generally slowed leftward initiation times. These abnormalities were more evident during visible than invisible trials, suggesting that perceptual aspects of the emerging figure disrupt patients' ability to guide motor performance. These results suggest that combining a computerized tablet with a simple copying task can provide new and clinically useful information, particularly with regard to motoric aspects of visual neglect. Such simple naturalistic tasks, in turn could lead to the development of shorter, more sensitive, and more clinically relevant assessments of visuomotor disorders.