Visual perturbations temporally tune balance retention and associated tactile processing

Abstract

AbstractPredictive processes are key components for the sensorimotor control of human movement. One characteristic phenomenon that arises around human movement is that somatosensory processing on moving limbs is modulated by being either enhanced or suppressed. This modulation is thought to arise from an interplay in the reliance between predictive and feedback signals that are relevant for the action. While this interplay can characterize tactile modulation during upper-limb goal-directed movements, less is known about how it functions during complex whole-body movements in dynamic environments. We here examine tactile modulation during upright stance that can be visually perturbed in a predictable or unpredictable manner. Participants were immersed in a virtual room, which could move in a predictable or unpredictable manner. We probed tactile processing via a vibrotactile stimulus delivered to the participants’ calf muscle, through which we assessed detection thresholds shortly before and after the perturbation. Meanwhile, human movement was assessed by measuring the center of pressure and head kinematics. As expected, anticipatory postural behavior preceded the predictable perturbations, whereas postural reactions were evident after both perturbation types. Tactile processing was hampered whenever participants were standing quietly relative to a sitting baseline. Tactile processing was not modulated by the predictability of the perturbation, but it was temporally tuned throughout the task, being enhanced after the onset of the perturbation. These results demonstrate that tactile signals can be dynamically modulated during complex whole-body movements, supporting the notion that tactile processing reflects an interplay between predictive and feedback signals.New and noteworthyWe demonstrate temporal modulation of tactile processing at lower limbs during postural responses to visual perturbations. Tactile signals are generally suppressed during standing than sitting, but this suppression recovers shortly before the body is about to respond to a visual perturbation that challenges upright stance. Our results suggest that tactile processing during balance retention within complex environments is modulated by an interplay between feedforward and feedback signals.