PUB - Publikationen an der Universität Bielefeld

Human manual actions are selected based on object properties but also goal-directed and habitual constraints. Although the goal-directed constraints have extensively been studied, little is known about habitual constraints. In this experiment, we investigated the neurophysiological mechanisms of grasping habits during motor planning. Twenty-two right-handed volunteers were asked to grasp a handle (habitually or non-habitually) and then rotated the handle (i.e., the end with a pointing marker) to a target position. In the habitual trials, participants grasped the handle with their thumb toward the pointing marker. In the non-habitual trials, participants grasped the handle with their thumbs away from the pointing marker. Movement timing parameters (reaction, reach, and rotation time) and movement-related cortical potentials (MRCPs) were recorded. Behaviorally, reaction, reach, and rotation times were shorter for habitual than for non-habitual grasp-ing (all F(1,21)s > 7.3; all ps < .05). Neurophysiologically, in the time window 500 ms before movement onset, posterior MRCPs were more negative-going for the non-habitual than for the habitual grasping (t(21) = 3.87; p < .001). Anterior MRCPs were similar between habitual and non-habitual grasping (t(21) = 0.98; n.s.). Furthermore, the mean amplitude of posterior MRCPs was negatively correlated with the reaction time for right-hand movements in the preparation of both habitual (r(20) = -0.45; p < .05) and non-habitual grasping (r(20) = -0.52; p < .05) but not for left-hand movements (all r(20)s < 0.1; n.s.).Our results suggest that movement preparation is affected by grasping habits. Instead of the anterior MRCPs, the posterior cortical activities during movement preparation are suggested to represent the grasping habits.