Abstract
A multitude of sensory events bombard our sensory systems at every moment of our lives. Thus, it is important for the sensory cortex to gate unimportant sensory events. Similarly, tactile suppression is a well-known phenomenon (Rushton et al., 1981; Buckingham et al., 2010). Tactile gating is a reduced ability to detect tactile events on the skin before and during movement. Previous experiments (Chapman et al., 1987) found detection rates decrease just before and during finger abduction and decrease according to the proximity of the moving effector. The present study examined the changes in tactile detection that occur during a reach and grasp. Participants were recruited (n=14) to perform reach and grasp movements to a cylinder (2.5 cm) that randomly changed location. Custom-built micro-motors were taped to the dorsal surfaces of the proximal phalanges of the index finger, the fifth digit and to the forearm. This arrangement was repeated on the left limb. A motor vibrated per trial relative to a "go" tone. The left limb remained at rest. Detection rates at the right fifth digit and forearm decrease dramatically before movement onset (no reduction at the index finger). These results indicate that the task affects gating dynamics (Williams & Chapman, 2002). Importantly, the CNS is able to modify input gating independently at multiple sites and does so before movement onset. Therefore, this indicates feed-forward mechanisms at work in sensorimotor networks.Acknowledgments: BCKDF, CFI, NSERC