An image-motion model of pursuit. (A) Target and eye motion during a “step-ramp” target motion, showing the image velocity and accelerations that provide inputs for pursuit. (B) The original three-pathway, image-motion model. The “speed filter” is part of a pathway that is sensitive to image speed. The “onset filter” is part of a pathway that is sensitive only to the onset of motion. The “accel filter” is part of a pathway that is sensitive to smooth image acceleration. (C) Black, red, and green traces show typical eye velocity data and the predictions of the full image-motion model and the model without the acceleration pathway for a step of target speed from 0 to 15 deg/s. (D) Representative time-varying firing rates for an MT neuron during ramp increases and decreases in target speed in an anesthetized monkey. (E) Responses of model MT neurons with the same range of acceleration-deceleration asymmetry found in the data. (F) Decoded target speed and acceleration for a model population of MT neurons with a range of preferred speeds and acceleration-deceleration asymmetries. Figures are modified, with permission from Krauzlis and Lisberger (1989), Lisberger and Movshon (1999), and Lisberger (2015).