Effect of OPN transmitter type on saccades. (A) and (B) show simulated position and velocity traces of a single saccade. When OPNs are glycinergic, the saccade (thick line) is fast (peak speed about 450 deg/s), and starts with a short latency (4.6 ms). After OPN lesion (dotted gray line), the saccade latency and accuracy are unaffected, but saccade slows down by about 18% because the loss of the co-agonist at the NMDAR reduces the gain of the Glu input. When OPNs are made GABA-ergic, saccade (dashed line) starts much later (38.8 ms) and is much slower (by 54%). This difference between the GABA traces and the OPN lesion traces are due to the much slower time course of decay of the GABAA receptor (C).