9420525 Weerasuriya Fast movements appear to be "stereotyped," yet high speed videotaping reveals significant variability in stereotyped behaviors. Fast movements are usually composed of several separate patterns of muscle coordination called "motor synergies." For example, the rapid movements of a frog snapping at a worm, which take less than 1/6th of a second, is composed of a "lunge synergy" (jumping towards the worm) together with the "jaw-tongue synergy" (the jaw opens, the tongue projects to hit the worm, the tongue retracts bringing the worm into the mouth and the jaw closes). This study is designed to understand how the brain coordinates multiple synergies, and how synergies that occur later in the behavior use feedback to compensate for inaccuracies of synergies that occur earlier in the behavior. The study will involve analysis of the behavior by high speed video taping, and recording of signals from the muscles controlling the behavior and the parts of the brain and spinal cord controlling the muscles. Studies already done by these investigators show that both synergies are variable, and that tongue projection can compensate for inaccuracy in the lunge. Data collected from the study will be used in neural network modeling of adaptability and coordination of rapid movements. The results of this study could provide new insights into the control of rapid limb movements by the brain and control of robots.
