Where was my arm again? Memory-based matching of proprioceptive targets is enhanced by increased target presentation time.

Our sense of proprioception is vital for the successful performance of most activities of daily living, and memory-based joint position matching (JPM) tasks are often utilized to quantify such proprioceptive abilities. In the present study we sought to determine if matching a remembered proprioceptive target angle was influenced significantly by the length of time given to develop a neural representation of that position. Thirteen healthy adult subjects performed active matching of passively determined elbow joint angles (amplitude = 20 degrees or 40 degrees extension) in the absence of vision, with either a relatively "short" (3 s) or "long" (12 s) target presentation time. In the long condition, where subjects had a greater opportunity to develop an internal representation of the target elbow joint angle, matching movements had significantly smaller variable errors and were associated with smoother matching movement trajectories of a shorter overall duration. Taken together, these findings provide an important proprioceptive corollary for previous results obtained in studies of visually-guided reaching suggesting that increased exposure to target sensory stimuli can improve the accuracy of matching performance. Further, these results appear to be of particular importance with respect to the estimation of proprioceptive function in individuals with disability, who typically have increased noise in their proprioceptive systems.