Coordinated control of reaching and grasping during prehension movement

Abstract

In this paper, we investigate coordinated control of human reaching and grasping during the prehension movements. The interaction between reaching and grasping has been investigated by using visual perturbations that unexpectedly change size or position of an object when executing the movement. Those studies have reported that both of reaching and grasping interact each other. However, the interaction may include some properties in visual information processing for physical properties of an target object. Thus, the interaction should be examined without the visual perturbations because the detail of the interaction between reaching and grasping is still unclear. From this point of view, the influence from reaching to grasping have been directly investigated by using mechanical perturbations. While, the influence from grasping to reaching have never been examined. In this study, we examined the influence that grasping affects reaching by giving mechanical perturbations to the finger tips during the movement. As a result, we found that humans adjust the speed of reaching based on the changes in grasping perturbed by the mechanical perturbations. Moreover, both the movement times of grasping and reaching are highly correlated even when grasping was perturbed by the perturbations. Consequently, we confirmed the temporally-coordinated adjustment from grasping to reaching during the prehension movement. This result indicates that the previously proposed control schemes can not explain our findings. This finding is quite important for building a computational model of the coordinated control of human reaching and grasping. © 2008 Springer-Verlag Berlin Heidelberg.