Fig. 5 Illustration of the FEM responses (A and B) and SEM responses (C and D) that would result from the neural innervation patterns depicted. The top left curves and the right dashed curves are plots of instantaneous firing rate vs. time. The equation relates neural firing frequency (R) with eye position (θ) and velocity (dθ/dt). Note that the overdamped nature of muscle and eyeball plant dynamics produces sluggish responses to a simple step (A) or ramp (C) change in firing frequency. To generate a proper FEM (saccade), a pulse-step is required (B). To generate a proper SEM (pursuit), a step-ramp is required (D). (Robinson DA: Oculomotor control signals. In Lennerstrand G, Bach-y-Rita P (eds): Basic mechanisms of ocular motility and their clinical implications. New York: Pergamon Press, 1975)