Guided by touch: Tactile Cues in Hand Movement Control

Abstract

Traditionally, touch is associated with exteroception and is rarely considered a relevant sensory cue for controlling movements in space, unlike vision. We developed a technique to isolate and evaluate tactile involvement in controlling sliding finger movements over a surface. Young adults traced a 2D shape with their index finger under direct or mirror-reversed visual feedback to create a conflict between visual and somatosensory inputs. In this context, increased reliance on somatosensory input compromises movement accuracy. Based on the hypothesis that tactile cues contribute to guiding hand movements, we predicted poorer performance when the participants traced with their bare finger compared to when their tactile sensation was dampened using a smooth finger splint. The results supported this prediction. EEG source analyses revealed smaller current in the presumed somatosensory cortex during sensory conflict, but only when the finger directly touched the surface. This finding suggests the gating of task-irrelevant somatosensory inputs. Together, our results emphasize touchs involvement in movement control, challenging the notion that vision predominantly governs goal-directed hand or finger movements.