Abstract
When we move our ability to detect tactile events on the moving limb is reduced. This process, known as movement-related tactile suppression, prevents unimportant sensory information from bombarding our central nervous system. This study explored whether movement-related suppression can be modulated according to task-relevance. In three experiments participants performed volitional self-driven (Experiment 1-3) and motor-driven (Experiment 1-2) reaching and grasping movements. Over the course of the movement, weak electrical stimulation was presented at task-relevant (i.e., index finger and thumb) and irrelevant sites (i.e., forearm) on the moving limb. In Experiment 1, participants displayed reduced detectability during movement (90% resting detection). This was true for all locations on the moving limb irrespective of task-relevance and during both self and motor-driven movements. In Experiments 2 and 3 a range of stimulus amplitudes were presented to one task relevant location during both self and motor-driven movements (Experiment 2) and to a task relevant and irrelevant site during self-driven movements (Experiment 3). This change in methodology allowed us to get a direct estimate of perceptual thresholds and asses the magnitude of movement-related tactile suppression. During both self and motor-driven movement, participants exhibited an increased perceptual threshold at the index finger (Experiment 2). The magnitude of suppression however, was greater at the irrelevant site (forearm) than at the relevant site (index finger; Experiment 3). Collectively these experiments suggest that although tactile suppression may be a general consequence of movement, this suppression can be modulated in a relevance-dependent manner.Acknowledgments: Supported by the Natural Sciences and Engineering Research Council of Canada