Abstract
Background: Online control processes are used during goal-directed movements to ensure that the limb reaches the target. Some of these online corrections require contrasting the position of the limb vs. the target (i.e., limb-target regulation) and have been presumed to require visual and proprioceptive inputs (Elliott et al., 2010). In the current study, we sought to investigate the importance of proprioceptive information for the implementation of online limb-target regulation processes. Methods: Thirteen participants were asked to perform rapid goal-directed reaches with tendon vibrators on the distal biceps and triceps brachii tendons and while wearing liquid-crystal goggles. Trials began with participants fixating to the start position. Then, the target appeared (30 cm amplitude) which prompted participants to initiate a saccade and a reaching movement. After that, the goggles were occluded. Then, on one third of the trials, the location of the target was shifted 3 cm closer to the participant. Before achieving peak limb velocity, participants were provided with a brief visual window (20ms), to see the original or jumped target (and their hand). On separate blocks of trials, tendon vibration was applied between trials to both the biceps and triceps, to decrease the sensitivity of the muscle spindles (Ribot-Ciscar et al., 1998). Results: Tendon vibration led to shorter movement times, which were explained by shorter limb deceleration phase durations. In contrast, seeing the jumped target location for 20 ms always led to a shift in the endpoint distributions (4.7 mm), as compared to when the original target was seen during the brief window regardless of the presence of vibration. Conclusion: While the proprioceptive perturbation did influence the motor performance, the limb-target regulation processes associated with the target jump did not significantly differ across tendon vibration conditions. Altogether, online limb-target regulation processes are predominantly visuomotor in nature.
Meeting abstract presented at VSS 2016