Fig. 10 Basic closed-loop diagram of the SEM mode of the version subsystem (heavy lines) superimposed on the block diagram of the total ocular motor control system. The pursuit control signal, conjugate retinal error velocity, is sent to the cortex, and the decision to move the eyes is forwarded to the pons, where the motor commands are generated and passed on to the ocular motor nuclei (OMN). This innervation causes the extraocular muscles (EOM) to move the eye with an SEM and change relative eye velocity. Assuming no change in head position, this new absolute eye velocity summates with target velocity at the retina to produce zero retinal error velocity.