Plenary Talk (sponsored by G.tec)

In our previous study, it was shown that the direction of asymmetry for bilateral transfer is measurement dependent. This study aimed to gain more insight into the relationship among the measures of movement duration, trajectory length, initial direction, duration of corrective movements, and movement smoothness. Subjects were required to make point-topoint drawing movements while adapting to a visual distortion resulting in visual feedback with a 45° rotation and 2 gain of pen movements. We examined performance of the non-dominant hand after practice of the dominant hand of half of the subjects, while performance of the dominant hand was examined after practice with the non-dominant hand of the other half of the subjects. To assess the relationships between performance improvements, correlations of change rates among the measures were analyzed. The results showed that the change of movement time is associated with movement smoothness in RR (right hand training, right hand testing) condition, with duration of corrective movement in LL (left hand training, left hand testing) condition, with both movement smoothness and duration of corrective movement in RL (right hand training, left hand testing) condition, and is not associated with any other measures in LR (left hand training, right hand testing) condition. The results suggest that there are different patterns of transfer at kinematic level for the four learning conditions. Furthermore, the occurrence of the asymmetry of bilateral transfer may be caused by the fact that the untrained non-dominant hand can use more information than the untrained dominant hand from the trained opposite hand to improve performance. Generalization of Dynamic Adaptation between Bilateral and Unilateral Movement Conditions. Jinsung WANG, Department of Human Movement Sciences, University of Wisconsin 53201, Milwaukee, WI, USA {[email protected]} Abstract. The efficacy of bilateral training for improving unilateral performance has recently been questioned by a study which demonstrated that bilateral adaptation to a novel dynamic condition during targeted reaching movement facilitated subsequent unilateral performance, but only to a limited extent. However, findings from another study indicated nearly complete transfer of novel visuomotor adaptation from a bilateral to a unilateral condition. The observed discrepancy may be attributed to the fact that the two studies examined the extent of generalization in different ways. Thus, the present study attempted to investigate the extent of generalization of novel dynamic adaptation between bilateral and unilateral conditions again, but by employing the experimental paradigm used in the latter study. The task employed in the present study was to make targeted reaching movement under a novel force field condition, with either one arm or both arms simultaneously. Results indicated poor performance with either arm during the bilateral session, which indicated some bilateral interference effects. However, the unilateral The efficacy of bilateral training for improving unilateral performance has recently been questioned by a study which demonstrated that bilateral adaptation to a novel dynamic condition during targeted reaching movement facilitated subsequent unilateral performance, but only to a limited extent. However, findings from another study indicated nearly complete transfer of novel visuomotor adaptation from a bilateral to a unilateral condition. The observed discrepancy may be attributed to the fact that the two studies examined the extent of generalization in different ways. Thus, the present study attempted to investigate the extent of generalization of novel dynamic adaptation between bilateral and unilateral conditions again, but by employing the experimental paradigm used in the latter study. The task employed in the present study was to make targeted reaching movement under a novel force field condition, with either one arm or both arms simultaneously. Results indicated poor performance with either arm during the bilateral session, which indicated some bilateral interference effects. However, the unilateral performance following bilateral training was superb from the beginning of the session, indicating a substantial amount of transfer from bilateral to unilateral conditions. These findings confirm that bilateral training is an effective method for improving unilateral performance. Characterizing synergies of grasping in the human hand. Harshavardhan A. AGASHE and José L. CONTRERAS-VIDAL, Graduate Program in Neuroscience and Cognitive Science, Department of Kinesiology, and Fischell Department of Bioengineering, University of Maryland, College Park, MD 20740 USA {[email protected], [email protected]}