Abstract
BackgroundWhen exposed to a novel dynamic perturbation, participants adapt by changing their movements’ dynamics. This adaptation is achieved by constructing an internal representation of the perturbation, which allows for applying forces that compensate for the novel external conditions. To form an internal representation, the sensorimotor system gathers and integrates sensory inputs, including kinesthetic and tactile information about the external load. The relative contribution of the kinesthetic and tactile information in force-field adaptation is poorly understood.MethodsIn this study, we set out to establish the effect of augmented tactile information on adaptation to force-field. Two groups of participants received a velocity-dependent tangential skin deformation from a custom-built skin-stretch device together with a velocity-dependent force-field from a kinesthetic haptic device. One group experienced a skin deformation in the same direction of the force, and the other in the opposite direction. A third group received only the velocity-dependent force-field.ResultsWe found that adding a skin deformation did not affect the kinematics of the movement during adaptation. However, participants who received skin deformation in the opposite direction adapted their manipulation forces faster and to a greater extent than those who received skin deformation in the same direction of the force. In addition, we found that skin deformation in the same direction to the force-field caused an increase in the applied grip-force per amount of load force, both in response and in anticipation of the stretch, compared to the other two groups.ConclusionsAugmented tactile information affects the internal representations for the control of manipulation and grip forces, and these internal representations are likely updated via distinct mechanisms. We discuss the implications of these results for assistive and rehabilitation devices.
Highlights
When exposed to a novel dynamic perturbation, participants adapt by changing their movements’ dynamics
We compared the positional errors between four stages of exposure to the perturbation: end of the Baseline session (Late Baseline- LB), beginning of the Adaptation session (Early AdaptationEA), end of the Adaptation session (Late AdaptationLA), and the beginning of the Washout session (Early Washout- EW)
In line with a previous study that showed an increase in the grip force-load force ratio when adding a skin-stretch in the context of interaction with elastic objects [4], here we found that skin-stretch in the same direction of the force increased the applied grip force per amount of load
Summary
When exposed to a novel dynamic perturbation, participants adapt by changing their movements’ dynamics This adaptation is achieved by constructing an internal representation of the perturbation, which allows for applying forces that compensate for the novel external conditions. Studies showed that sensory information can be used differently to form internal representation for manipulation and grip force control [5,6,7]. With a sudden removal of the perturbation, the participants exhibit aftereffects, which demonstrate the construction of an internal representation that was used for manipulation force control [11]. We will use this approach to investigate the effect of augmented tactile information on the way participants adapt to force-field perturbation
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