Abstract
Apraxia is a disorder involving the inability to pantomime or imitate hand gestures; scores for which are frequently derived individually and composite score calculated as performance metric. Such composite scores may obscure important differences among the gestures. Some work suggests movements in peri-personal space toward the body are made more quickly than those in extra-personal space. Furthermore, the "aiming" literature suggests that movements towards and away are fundamentally different. Therefore this study investigated whether pantomiming tool use was performed equally well if movements toward versus away from the body were assessed. Patients with stroke in the Left (LH) Hemisphere [N=54] or Right (RH) Hemisphere [N=49] were tested and compared to 28 healthy controls. The results indicate that pantomimes involving movement towards the body (Tweezers, Fork, Comb, and Toothbrush) were performed more accurately compared to pantomimes away from the body (Hammer, Knife, Watering Can, and Flipper). While the results revealed that the LH group was the least accurate in gesture performance, the effect of movement direction was comparable across the three groups. These findings support previous work showing the importance of movement direction in peripersonal spaces in determining the accuracy of movement. This direction effect however appears to be independent of apraxia severity, since the direction effect was comparable in LH apractic patients and the other two groups.Acknowledgments: NSERC, Heart and Stroke Foundation of Ontario