Modelling Control of Eye Orientation in Three Dimensions

A consideration of velocity-position integration and its interaction with the oculomotor plant in three dimensions has led to two opposing conceptual models. An emergent property of the vector integrator model is its ability to predict subtle aspects of saccadic trajectories and eye position dependent effects of the response characteristics of the angular vestibulo-ocular reflex. The dynamical system representing changes in eye velocity and orientation can be given by Isaac Newton’s equation of motion in the inertial space fixed frame. The justification for this approximation comes from early biomechanical eye plant models that assumed rectus muscle tendons to be effectively attached to the globe by intermuscular membranes and their bellies to be relatively free to move about the orbit during eye rotations. For large eye deviations, more detailed affects of eye orientation on the muscle torque could be handled by incorporating the length-tension characteristics of the muscle.