BELANGER, Jim H; Louisiana State University, Baton Rouge: Strategies and tactics in motor control

Vertebrates and arthropods share the common problem of controlling a rigid, articulated skeleton using neurally-controlled, striated muscle. Since this condition has arisen independently in the two groups, there is no reason to assume, a priori, that the control mechanisms used by the two groups will be the same. In comparing the two groups, it is helpful to distinguish between motor control tactics – the mechanisms an organism uses to control individual muscles – and motor control strategies – those overall aspects of the neuromechanical system the organism attempts to control. We are investigating these issues using muscle and limb simulations, combined with physiological experiments on both isolated muscles and intact, behaving animals. The data suggest that there are fundamental differences in the tactics used by vertebrates and arthropods. For example, gain control by myotropic modulation appears to be a major tactic in arthropods, but is virtually absent in vertebrates. It is still very much an open question what strategies the two groups use, and whether they are similar or different.