Fig. 8.

Stimulation of the nigra during the delay period alters the variability of saccadic eye movement endpoints and lengths of saccades in the absence of visual information. The arrangement is identical to that of Fig. 4. Data are from experiments in which both the memory-guided and visually guided saccade tasks were performed. Visual no stim indicates visually guided trials without stimulation of the nigra; visual stim indicates trials in which stimulation occurred. Memory no stim indicates trials in which memory-guided saccades were performed and stimulation of the nigra did not occur; memory stim indicates trials in which nigral stimulation occurred. **P < 0.05, indicating that the distribution was significantly more variable with stimulation than without. The red arrows show the example result that appears in Fig. 6.