RT Journal Article T1 Inertial torque during reaching directly impacts grip-force adaptation to weightless objects A1 Giard, T. A1 Crevecoeur, F. A1 McIntyre, J. A1 Thonnard, J. L. A1 Lefèvre, P. AB A hallmark of movement control expressed by healthy humans is the ability to gradually improve motor performance through learning. In the context of object manipulation, previous work has shown that the presence of a torque load has a direct impact on grip-force control, characterized by a significantly slower grip-force adjustment across lifting movements. The origin of this slower adaptation rate remains unclear. On the one hand, information about tangential constraints during stationary holding may be difficult to extract in the presence of a torque. On the other hand, inertial torque experienced during movement may also potentially disrupt the grip-force adjustments, as the dynamical constraints clearly differ from the situation when no torque load is present. To address the influence of inertial torque loads, we instructed healthy adults to perform visually guided reaching movements in weightlessness while holding an unbalanced object relative to the grip axis. Weightlessness offered the possibility to remove gravitational constraints and isolate the effect of movement-related feedback on grip force adjustments. Grip-force adaptation rates were compared with a control group who manipulated a balanced object without any torque load and also in weightlessness. Our results clearly show that grip-force adaptation in the presence of a torque load is significantly slower, which suggests that the presence of torque loads experienced during movement may alter our internal estimates of how much force is required to hold an unbalanced object stable. This observation may explain why grasping objects around the expected location of the center of mass is such an important component of planning and control of manipulation tasks. SN 0014-4819 YR 2015 FD 2015-11-01 LK https://hdl.handle.net/11556/3465 UL https://hdl.handle.net/11556/3465 LA eng NO Giard , T , Crevecoeur , F , McIntyre , J , Thonnard , J L & Lefèvre , P 2015 , ' Inertial torque during reaching directly impacts grip-force adaptation to weightless objects ' , Experimental Brain Research , vol. 233 , no. 11 , pp. 3323-3332 . https://doi.org/10.1007/s00221-015-4400-z NO Publisher Copyright: © 2015, Springer-Verlag Berlin Heidelberg. NO This research was supported by a grant from the European Space Agency (ESA), PRODEX and IAP (Belspo), and ARC (Belgium). J. McIntyre is supported by Université Paris Descartes, the Centre National de la Recherche Scientifique, the Conseil Régional Ile de France and by a grant from the Centre National d’Etudes Spatiales (CNES). DS TECNALIA Publications RD 26 jul 2024