Making sense of touch: spatial tactile cues promote efficient visuosomatosensory integration and restore motor accuracy under sensory conflict

Abstract

Effective interaction with complex environments relies on integrating somatosensory and visual signals into coherent spatial representations of the body in external space. When these signals conflict, as during movement under mirror-reversed visual feedback, motor performance deteriorates. Under such conflict, visual information typically facilitates motor performance, whereas tactile feedback impairs it. Here, we tested whether providing tactile input with explicit spatial structure renders visuo-somatosensory integration functionally relevant and stabilizes motor behaviour under sensory conflict. Healthy adults performed a mirror-tracing task, tracing a shapes contour with the index finger while tactile feedback conveyed either motion-related cues alone or additional discrete spatial landmarks aligned with the outline. Spatially structured tactile cues preserved accuracy and smoothness relative to motion-related tactile input, indicating more effective online motor control. EEG source analyses further revealed that, when spatial tactile cues were present, somatosensory activity increased and functional connectivity became more focal within sensorimotor networks. In contrast, when absent, sensory conflict was associated with widespread reductions in cortical activity, including in somatosensory areas, and with a diffuse functional connectivity pattern consistent with elevated sensorimotor uncertainty. Together, these findings demonstrate that spatial tactile cues bias hand-displacement encoding toward an external reference frame, promote efficient visuo- somatosensory integration and mitigate the detrimental impact of sensory conflict on motor action.