Figure 5. Population spike density functions (overlap condition). A–D, Automatic neurons (n = 23) on trials with saccades toward their preferred (A–B) and null (C, D) directions. E–H, volitional neurons (n = 64) on trials with saccades toward their preferred (E, F) and null (G, H) directions. Left (A, C, E, G) and right (B, D, F, H) columns show activity aligned with stimulus appearance and saccade initiation, respectively. Thick lines indicate population averages. Thin lines indicate 95% confidence interval. Black horizontal bars under the x-axes indicate the prestimulus period (0–80 ms after stimulus appearance) in the left column (A, C, E, G) and presaccade period (−90 to −30 ms from saccade initiation) in the right column (B, D, F, H). Pro, Prosaccade; Anti, antisaccade.