Large-amplitude, head-restrained saccade adaptation. Summary of primary saccades made during preadaptation, adaptation, postprobe, and recovery segments of backward (A, B) and forward (C, D) adaptation experiments from 2 monkeys (P, Q). Black triangles: probe trials; gray squares: adaptation trials; open diamonds: recovery trials.

Gaze, saccade, head contribution, and total head amplitudes of the primary gaze shifts made during preadaptation, adaptation, and postprobe segments of backward adaptation experiment Q3. A–D: data from gaze shifts in which the eyes were deviated leftward (head deviated toward T₁) in the orbits (mean IEP = −13.0 ± 1.1°). E–H: data from gaze shifts in which the eyes were deviated rightward (head deviated away from T₁) in the orbits (mean IEP = 14.7 ± 1.0°). Black triangles: probe trials; gray squares: adaptation trials.

Gaze transfer experiment (P4). Gaze shifts were initiated from all 3 eye positions in the preadaptation phase. During the initial adaptation phase gaze shifts were initiated only from the leftward eye position (blue). After about 300 trials novel eye positions (centered: green; rightward: red) were introduced. Note that the gaze amplitude at the end of the initial adaptation and the novel eye position phases is similar; however, the saccade, head contribution, and total head movements are not.

Summary of the change in gaze (A, E), saccade (B, F), head contribution (C, G), and total head amplitude (D, H) for gaze shifts initiated from the centered eye position from 28 sessions (17 backward and 11 forward). The difference (±SD) between the preadaptation probe mean and the postadaptation mean (black bars) or postprobe mean (gray bars) is illustrated. (*) denotes a change in movement amplitude between pre- and postmeans (t-test, P < 0.05).

Gaze, saccade, head contribution, and total head amplitudes of the primary gaze shifts made during preadaptation, adaptation, postprobe, and recovery segments of backward adaptation experiment Q1. A–D: data from gaze shifts in which the eyes were deviated leftward (head deviated toward T₁) in the orbits (mean initial eye position [IEP] = −14.9 ± 2.0°). E–H: data from gaze shifts in which the eyes were deviated rightward (head deviated away from T₁) in the orbits (mean IEP = 12.5 ± 1.0°). Black triangles: probe trials; gray squares: adaptation trials; open diamonds: recovery trials.

Summary of the change in gaze (A, E), saccade (B, F), head contribution (C, G), and total head amplitude (D, H) for gaze shifts initiated with the eyes and head not aligned during forward adaptation experiments. Data were extracted from the same 11 sessions shown in Fig. 4, E–H. The difference (±SD) between the preadaptation probe mean and the postadaptation mean (black bars) or postprobe mean (gray bars) is illustrated. (*) denotes a change in movement amplitude between pre- and postmeans (t-test, P < 0.05).

Summary of the change in gaze (A, E), saccade (B, F), head contribution (C, G), and total head amplitude (D, H) for gaze shifts initiated with the eyes and head not aligned during backward adaptation experiments. Data were extracted from the same 28 sessions shown in Fig. 4. The difference (±SD) between the preadaptation probe mean and the postadaptation mean (black bars) or postprobe mean (gray bars) is illustrated. (*) denotes a change in movement amplitude between pre- and postmeans (t-test, P < 0.05).

Eye–head coordination during adapted vs. control movements. Gaze shifts were matched for gaze amplitude and initial orbital eye position (“leftward,” “centered,” “rightward”). A–C: mean (±SD) control saccade plotted as a function of saccades during adapted movements. D–F: mean (±SD) control head contribution plotted as a function of head contribution during adapted movements. Data from monkey Q (▴), monkey S (), and monkey P (▪) are shown. Black symbols represent comparisons for forward adaptation experiments. Gray symbols represent comparisons for backward adaptation experiments. Open symbols represent statistically significant differences between adapted and control values (Mann–Whitney U test, P < 0.05).

Gaze (green), eye (red), and head (blue) positions as functions of time during a forward adaptation session (Q3) in which the eyes were initially centered in the orbits (±5°). Each panel illustrates a gaze shift made at a different stage of the adaptation process. Position traces are aligned at gaze onset (“100 ms”) in each plot. E–H: gaze, saccade, head contribution, and total head amplitudes, respectively, of the primary gaze shifts made during preadaptation, adaptation, and postprobe segments of experiment Q3. Individual examples in A–D are indicated with labeled arrows. Black triangles: probe trials; gray squares: adaptation trials.

A–D: gaze (green), eye (red), and head (blue) positions as functions of time during a backward adaptation session (Q1) in which the eyes were initially centered in the orbits (±5°). Each panel illustrates a gaze shift made at a different stage of the adaptation process. Position traces are aligned at gaze onset (“100 ms”) in each plot. E–H: gaze, saccade, head contribution, and total head amplitudes of the primary gaze shifts made during preadaptation, adaptation, postprobe, and recovery segments of experiment Q1. Individual examples in A–D are indicated with labeled arrows. Black triangles: probe trials; gray squares: adaptation trials; open diamonds: recovery trials.

A–C: schematic diagrams of trial types used. In each panel, gaze position is represented by a thin black line and plotted as a function of time. Below this trace, targets are represented by thick bars indicating when within the trial each target was illuminated and extinguished. In each case, trials began with the illumination of a head-mounted laser (light gray bar) followed by presentation of T₀. If behavioral contingencies were satisfied, the head-mounted laser and T₀ target were extinguished and a second target (T₁) was illuminated at one of the spatial locations shown in E (black circles). A: the T₁ target remained illuminated for the duration of the “delayed” trials. B: during “probe” trials, the T₁ target was extinguished when the line of sight moved beyond a computer-defined window (“position criterion”) surrounding T₀. C: “adaptation” trials were similar to probe trials until 20 ms after the position criterion was satisfied, at which time T₁ was turned off and a target at location T₂ was illuminated. D: recovery trials were identical to adaptation trials except that the T₁ target was reilluminated and remained illuminated for the duration of the trial. E: target locations used during adaptation and probe trials. F–H: example target and reward window locations during probe (F), adaptation (G), and recovery (H) trials during a backward adaptation experiment. See text for further details.