Acute Loss of Tactile Input Leads to General Compensatory Changes in Eye-Hand Coordination during Object Manipulation.

Abstract

Current models of motor control emphasize the critical role of sensory feedback, as demonstrated by movement coordination deficits following sensory impairment. When both vision and touch are available for object-oriented manual behaviors, they serve distinct roles; vision guides the execution of planned movements, while touch provides more direct feedback on hand-object interactions. The impact of losing somatosensory feedback on eye-hand coordination during dexterous object manipulation tasks has not been thoroughly studied. Conceivably, vision is recruited to compensate for the feedback lost when touch is abolished based on the dexterity demands of the behavior. To investigate this, we tested healthy participants of either sex on a manual dexterity task requiring the movement of small metal pegs, both before and after the administration of digital anesthesia, which selectively abolished cutaneous sensations in the fingertips while preserving motor function. We recorded participants' gaze and hand positions. Despite loss of cutaneous feedback, participants successfully completed the pegboard task. However, they exhibited significantly longer trial times and altered force profiles. Notably, acute somatosensory loss triggered a rapid shift in visual behavior, characterized by a tighter coupling between gaze and hand positions across all task actions, even those not directly involving object manipulation. These changes, which occurred with anesthesia of the dominant and nondominant hands, were not evident with sham (saline) injections. Our findings underscore the contributions of sensory feedback to force control in service of dexterous object manipulation and reveal the nonselective nature of compensatory gaze-hand coordination processes.