Studies from our laboratory have shown that monkeys make faster and earlier saccades when reward is expected and that many basal ganglia neurons change their visuo-saccadic activity accordingly. We hypothesized that the reward-dependent signals are conveyed from the substantia nigra pars reticulata (SNr) to the superior colliculus (SC). In fact, we found that visual responses of many SC neurons were modulated by reward expectation (Ikeda et al. 2001 SFN). However, it would be saccadic, not visual, activity of SC neurons that can determine saccadic parameters. We therefore recorded 123 SC neurons that showed pre-saccadic activity. We found that SC pre-saccadic activity tended to be higher in rewarded trials than in non-rewarded trials (mean ratio: 1.15). Consistently with the data, the saccade velocity tended to be higher in rewarded trials than in non-rewarded trials (mean ratio: 1.07). These data suggest that saccades become faster when reward is expected because SC neurons fire more vigorously. However, ...