Article Figures & Data
Figures
- Figure 1.
Natural eye–hand coordination in the eye–hand task. a, The temporal sequence of events in the eye–hand task. Eyes were unconstrained. b, The inactivation site shown on the horizontal brain MRI slice. The bright spot indicates where MR visible gadolinium was injected in the same way as muscimol. c, The hand and eye positions of seven example trials in the eye–hand task are aligned to the go cue. Each pair of a solid and a dashed line in the same color represents the hand and eye positions of the same single trial. The arrows mark the positions of the central hand-fixation and the reach target. d, Reach and saccade endpoints for six target locations in the eye–hand task from an example pair of a control and an inactivation session. The saccades occurred under free-gaze condition in the absence of experimental requirements.
- Figure 2.
PRR inactivation shortens the amplitude of coordinated saccades and reaches but not of saccades executed alone. a, Reach and saccade amplitudes in three task conditions for each of six target locations. For each target, the mean amplitude and its 95% confidence interval are plotted for control versus inactivation reaches in the eye–hand task, control versus inactivation saccades in the eye–hand task, control versus inactivation reaches in the hand-only task, and control versus inactivation saccades in the saccade-only task, from left to right. The horizontal dashed line in each plot marks the target amplitude. b, Within-session means of reach and saccade amplitudes in the eye–hand task for the contralateral target, in control versus inactivation sessions. Each pair of a control and an inactivation session is connected with a solid line if their means are significantly different (p < 0.05), and with a dashed line otherwise.
- Figure 3.
PRR inactivation weakens the temporal correlation between spatially coordinated reaches and saccades. a, Saccade reaction times versus reach reaction times (RTs) for the contralateral target in the eye–hand task for all control versus inactivation trials. Each dot represents a single trial, and the lines are the linear regression. b, The mean and its 95% confidence interval of the correlation coefficient between saccade and reach RTs of all control versus inactivation trials for each of the six target locations. c, Within-session RT correlation coefficients for the contralateral target, in control versus inactivation sessions. Each pair of a control and an inactivation session is connected with a solid line if their coefficients are significantly different (p < 0.05), and with a dashed line otherwise.
Tables
Monkey Session no. No. of trials per target Eye–hand Hand-only Eye-only Control Inactivation Control Inactivation Control Inactivation Y 1 22 (21) 11 (10) 22 11 2 20 (20) 19 (17) 14 19 3 21 (20) 22 (18) 20 22 4 13 (12) 25 (21) 14 25 5 25 (25) 25 (25) 25 29 26 27 6 25 (24) 25 (23) 28 33 26 25 7 26 (24) 13 (12) 40 13 26 15 G 1 8 (7) 19 (17) 9 21 9 19 2 15 (12) 18 (6) 14 18 13 14 3 19 (15) 11 (8) 18 9 17 9 4 15 (12) 19 (17) 13 18 13 17 5 18 (17) 19 (17) 17 20 18 18 6* 258 (234) 266 (240) 33 53 34 57 Each session is a pair of control and inactivation that were typically separated by 1 d. The numbers in parenthesis indicate the number of trials in which both eye and hand positions at the onset of go cue were within 1 cm from the hand-fixation target. The italicized sessions and tasks are data previously presented in Hwang et al. (2012).
↵*Tasks were performed with only two targets (contralateral and ipsilateral). In the other sessions, tasks were performed with six targets.
- Table 2.
Summary statistics of inactivation effects on movement amplitude, reaction time, and movement duration (from top to bottom)
Changes in mean (mean, SEM, p) Changes in variance (mean, SEM, p) Changes in CC (mean, SEM, p) Reach_EH Saccade_EH Reach_HO Saccade_EO Reach_EH Saccade_EH Reach_HO Saccade_EO Movement amplitude Monkey Y: I −0.26 0.092 0.000 −0.21 0.083 0.001 −0.63 0.080 0.000 −0.07 0.075 1.000 −0.04 0.070 1.000 −0.06 0.088 1.000 −0.02 0.048 1.000 0.21 0.090 0.001 −0.24 0.109 0.012 IU −0.38 0.090 0.000 −0.01 0.147 1.000 −1.01 0.052 0.000 0.24 0.179 0.370 −0.02 0.077 1.000 −0.58 0.321 0.092 −0.05 0.044 1.000 −0.95 0.907 1.000 −0.07 0.112 1.000 CU −0.57 0.065 0.000 0.11 0.149 1.000 −1.46 0.081 0.000 −0.08 0.125 1.000 −0.32 0.082 0.000 0.34 0.361 1.000 −0.27 0.059 0.005 0.85 0.452 0.002 −0.17 0.126 0.294 C −0.59 0.068 0.000 −0.38 0.123 0.000 −1.68 0.079 0.000 −0.06 0.148 1.000 0.13 0.072 0.092 0.20 0.258 1.000 0.05 0.082 1.000 −1.38 0.886 0.180 0.27 0.135 0.066 CD −1.07 0.086 0.000 −0.13 0.099 0.335 −1.60 0.104 0.000 1.11 1.237 1.000 0.13 0.080 0.851 0.07 0.109 1.000 −0.05 0.134 1.000 −0.07 0.157 1.000 −0.04 0.184 1.000 ID −0.44 0.093 0.000 −0.08 0.085 0.986 −0.49 0.104 0.000 −0.02 0.074 1.000 0.05 0.089 1.000 0.00 0.098 1.000 −0.22 0.095 0.077 0.02 0.071 1.000 −0.02 0.113 1.000 Monkey G: I −0.12 0.082 0.232 −0.08 0.091 1.000 −1.57 0.190 0.000 0.05 0.091 1.000 −0.14 0.074 0.040 0.19 0.520 1.000 −0.45 0.184 0.137 −0.01 0.084 1.000 −0.01 0.078 1.000 IU −0.64 0.143 0.000 0.12 0.158 1.000 −1.78 0.152 0.000 0.43 0.155 0.001 0.26 0.150 0.202 0.09 0.210 1.000 −0.19 0.208 1.000 −0.29 0.258 1.000 0.31 0.252 0.528 CU −0.22 0.146 0.237 −0.23 0.235 1.000 −0.52 0.107 0.000 −0.16 0.179 1.000 0.18 0.146 0.545 1.31 0.876 0.156 −0.15 0.127 0.565 −0.15 0.271 1.000 −0.04 0.235 1.000 C −0.69 0.076 0.000 −0.44 0.104 0.000 −0.71 0.165 0.000 −0.08 0.296 1.000 −0.21 0.081 0.007 −1.87 1.446 0.007 −0.63 0.254 0.033 0.33 0.143 0.016 0.17 0.078 0.048 CD −0.31 0.135 0.005 0.05 0.184 1.000 −1.03 0.152 0.000 −0.15 0.147 0.856 0.18 0.170 1.000 0.53 0.347 0.199 −0.15 0.162 1.000 0.16 0.165 1.000 0.00 0.221 1.000 ID −0.11 0.124 1.000 0.20 0.129 0.214 −0.85 0.139 0.000 0.03 0.153 1.000 −0.28 0.154 0.053 0.02 0.128 1.000 −0.27 0.188 0.657 0.29 0.184 0.139 −0.22 0.194 0.564 Reaction time Monkey Y: I 2.74 4.133 1.000 3.75 3.899 1.000 24.24 9.128 0.001 −0.22 4.355 1.000 −0.84 0.505 0.095 0.94 0.602 0.094 −1.51 1.263 0.662 0.39 0.665 1.000 0.02 0.123 1.000 IU −3.24 4.147 1.000 3.49 4.850 1.000 30.30 8.487 0.000 −15.06 6.049 0.004 −0.40 0.313 0.468 1.55 0.780 0.013 −1.31 0.933 0.411 −1.38 1.188 0.912 −0.20 0.108 0.048 CU 0.50 3.488 1.000 −8.18 4.399 0.058 17.90 6.932 0.002 7.27 5.073 0.247 −0.36 0.198 0.073 −1.21 0.615 0.051 −0.75 0.554 0.579 1.38 0.982 0.258 0.16 0.133 0.516 C 16.02 6.204 0.000 16.54 7.925 0.019 9.08 6.646 0.394 −16.39 5.598 0.000 2.71 2.211 0.750 0.83 1.213 1.000 −0.83 0.981 1.000 −1.73 1.247 0.336 −0.26 0.109 0.018 CD 12.86 5.146 0.000 −18.04 11.528 0.156 28.45 6.440 0.000 −4.78 5.248 1.000 1.53 1.749 1.000 0.94 1.022 1.000 −0.66 0.860 1.000 −1.11 0.815 0.462 −0.08 0.200 1.000 ID 2.57 6.443 1.000 −22.35 7.071 0.000 −1.21 13.776 1.000 −7.81 4.163 0.046 −4.90 4.432 1.000 −1.12 0.644 0.128 −1.87 3.732 1.000 0.46 0.738 1.000 0.09 0.176 1.000 Monkey G: I −9.07 4.859 0.058 −24.72 3.846 0.000 −32.0 12.59 0.001 −9.13 5.878 0.165 −1.36 0.665 0.025 −0.33 0.579 1.000 −4.98 4.614 0.683 0.20 0.728 1.000 0.04 0.115 1.000 IU 27.81 17.450 0.161 0.54 5.916 1.000 2.33 12.68 1.000 5.71 8.678 1.000 7.75 7.653 1.000 −0.30 0.468 1.000 −6.62 3.936 0.008 1.48 1.324 0.750 0.04 0.136 1.000 CU −6.17 13.919 1.000 −8.56 9.404 1.000 16.74 13.045 0.451 −19.03 6.861 0.001 −2.77 2.074 0.423 −0.17 0.731 1.000 4.02 3.389 0.488 −0.22 0.475 1.000 −0.28 0.202 0.684 C −24.4 25.504 0.000 −15.83 3.673 0.000 −10.53 11.50 1.000 −9.82 4.969 0.027 1.68 1.745 1.000 −0.91 0.381 0.001 5.14 4.254 0.654 −0.67 0.249 0.000 −0.15 0.072 0.036 CD 32.61 19.249 0.110 30.90 8.990 0.000 9.54 11.743 1.000 −1.59 7.450 1.000 14.52 6.887 0.005 1.36 0.675 0.056 1.17 1.538 1.000 −0.32 0.729 1.000 0.12 0.189 1.000 ID 14.19 24.094 1.000 −5.38 7.306 1.000 1.23 12.414 1.000 −10.82 8.154 0.356 2.49 6.224 1.000 0.19 0.596 1.000 0.46 2.634 1.000 0.89 1.087 1.000 0.10 0.175 1.000 Movement duration Monkey Y: I −16.7 4.43 0.000 0.4 0.55 1.000 −15.7 4.38 0.000 0.4 0.53 1.000 −0.03 0.449 1.000 0.00 0.004 1.000 −0.07 0.326 1.000 0.00 0.005 1.000 0.09 0.140 1.000 IU −22.5 5.45 0.000 0.1 0.59 1.000 −28.7 4.34 0.000 0.8 0.64 0.622 −1.10 0.854 0.668 0.00 0.005 1.000 −0.46 0.304 0.805 −0.01 0.007 0.051 0.03 0.095 1.000 CU −28.9 5.64 0.000 0.3 0.87 1.000 −22.8 4.82 0.000 0.0 0.96 1.000 −3.45 1.196 0.000 −0.01 0.009 0.501 −0.17 0.472 1.000 −0.01 0.010 1.000 0.08 0.113 1.000 C −24.4 5.17 0.000 1.0 0.81 0.418 1.1 10.41 1.000 −0.2 0.99 1.000 −1.39 0.706 0.043 0.01 0.009 0.311 5.31 5.551 1.000 0.03 0.039 1.000 −0.03 0.163 1.000 CD −16.0 3.79 0.000 2.2 1.25 0.060 44.0 22.44 0.014 −1.5 1.16 0.404 −0.25 0.171 0.506 0.07 0.064 0.196 38.77 13.922 0.000 0.01 0.013 0.835 −0.07 0.206 1.000 ID −14.0 4.80 0.000 0.8 0.60 0.504 −10.5 4.74 0.016 2.1 1.08 0.039 −2.03 1.290 0.016 0.00 0.006 1.000 −0.52 0.362 0.550 0.01 0.012 0.557 −0.13 0.139 1.000 Monkey G: I −34.4 5.96 0.000 −3.6 1.58 0.006 −38.71 1.32 0.000 −1.6 0.88 0.076 −5.13 4.665 1.000 0.14 0.217 1.000 −3.57 3.723 1.000 −0.03 0.021 0.428 0.06 0.054 1.000 IU −8.0 7.55 0.829 −0.8 0.74 0.763 −13.0 9.95 0.383 1.6 0.92 0.095 0.43 0.799 1.000 0.01 0.008 0.139 −0.55 4.382 1.000 0.00 0.011 1.000 0.27 0.141 0.132 CU 3.1 9.81 1.000 −1.6 1.24 0.425 1.2 6.90 1.000 −1.8 1.32 0.302 −2.25 2.621 1.000 −0.04 0.040 0.959 −0.21 0.397 1.000 −0.02 0.029 1.000 −0.27 0.179 0.282 C −41.3 4.25 0.000 −0.8 0.52 0.145 −20.0 7.23 0.000 −0.4 0.87 1.000 −1.71 0.958 0.076 −0.02 0.016 0.151 2.05 1.406 0.257 0.02 0.024 1.000 −0.10 0.065 0.354 CD 2.4 10.06 1.000 −2.6 1.24 0.023 8.9 9.07 1.000 −2.0 1.29 0.151 0.19 2.339 1.000 −0.01 0.014 1.000 1.99 2.120 1.000 −0.02 0.012 0.271 0.06 0.204 1.000 ID −7.3 8.02 1.000 0.2 1.13 1.000 −10.6 6.24 0.099 −1.1 1.01 0.869 −0.68 0.792 1.000 0.01 0.012 0.623 −0.27 0.256 0.844 0.00 0.013 1.000 0.22 0.157 0.780 The left column indicates Monkeys Y and G targets (I, ipsilateral; IU, ipsilateral upward; CU, contralateral upward; C, contralateral; CD, contralateral downward; ID, ipsilateral downward). The top rows indicate the properties of a movement parameter (mean, variance, saccade-reach correlation coefficient), the task condition (EH, eye–hand task; HO, hand-only task; EO, eye-only task), and effectors (saccade and reach). Correlation coefficients between saccade and reach were measured only in the eye–hand task. Each triplet of numbers represents the mean, SE, and p value for the difference in the corresponding property of a movement parameter between all control and inactivation trials. A positive difference in means indicates an increase by inactivation. Triplets with a consistent, significant effect in both monkeys are bold. Triplets with a significant effect only in one monkey are italicized.
Monkey Reach reaction time (ms, mean ± SD) Saccade reaction time (ms, mean ± SD) Control Inactivation Control Inactivation Y I 268 ± 3.3 271 ± 2.5 220 ± 2.1 223 ± 3.4 IU 300 ± 3.1 296 ± 2.8 219 ± 2.4 222 ± 4.2 CU 302 ± 2.6 302 ± 2.3 218 ± 3.6 210 ± 2.5 C 289 ± 3.0 305 ± 5.4 220 ± 4.9 237 ± 6.1 CD 256 ± 2.5 269 ± 4.5 396 ± 7.5 378 ± 8.6 ID 250 ± 6.1 252 ± 2.1 312 ± 5.2 290 ± 4.8 G I 368 ± 3.8 358 ± 3.2 245 ± 2.8 221 ± 2.7 IU 400 ± 9.6 427 ± 14.5 229 ± 4.4 230 ± 3.9 CU 438 ± 10.9 433 ± 8.7 282 ± 6.7 273 ± 6.5 C 412 ± 3.6 388 ± 4.3 268 ± 2.9 252 ± 2.3 CD 409 ± 8.0 441 ± 17.5 283 ± 5.5 314 ± 7.2 ID 467 ± 16.7 482 ± 17.1 255 ± 5.3 250 ± 5.0 The means were computed across all control versus inactivation trials, for each target and each monkey. Means with a significant difference between control and inactivation (permutation test, p < 0.05 corrected for multiple comparison; see Table 2 for the statistical tests on the difference) were italicized.
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