Article Figures & Data
Figures
- Figure 1.
A, Experimental setup. Electromyogram was recorded from PM and PD. B, Typical simple reaching trial without VP and FF. C, NoVP trial with FF, either CW (red arrows) or CCW (blue arrows). D, VP trial without FF. Participants were requested to make a short pause at VP and proceed to the final target. E, VP ShortDwell trial with FF before and after VP. F, VP ShortDwell catch trial with FF unexpectedly turned off after VP. G, VP LongDwell trial with FF before and after VP. H, VP LongDwell catch trial with FF unexpectedly turned off after VP. The target would change color when the participants made movements within the instructed time window. For D–H, VP would change color when the participants made a pause at VP and the hand velocity dropped to <3 cm/s. For G, H, VP would change color again when the participant stayed at VP for 500 ms.
- Figure 2.
A, First trials of no VP movements with CCW (blue) and CW (red) FFs (NoVPFF) plotted with baseline (NoVP) trials (black) for all 18 subjects. B, Last trials of the same, note how the target overshoot is reduced in comparison with first trials. C, Distance traveled (path length) by hand during first and last trials. D, End-point target overshoot in the X direction in early and late trials. The thick black dot and star in C, D indicate the mean. There is a significant reduction in target overshoot and path length between early and late trials, which show hints of adaptation.
- Figure 3.
Distribution of actual dwell times for all subjects and all trials in (A) ShortDwell and (B) LongDwell blocks. Each bin corresponds to 50 ms. For ShortDwell, the trials with dwell times longer than 500 ms and for LongDwell, the trials with dwell times shorter than 500 ms or longer than 1500 ms were removed from the analyses.
- Figure 4.
A–C, Condition where FF was on before and after VP for both CW and CCW perturbations. D–F, Condition where FF was on before VP, but turned off after VP. VP baseline trials were included for comparison. A, D, Mean hand position in space. The dotted vertical line represents zero deviation. B, E, Mean X hand position across time from the onset of reach. The dotted lines in brown represent the mean VP exit time points. The plots in the dotted inset box (y-axis = [−2 2], x-axis = [0 600]) represent the mean X hand position immediately after VP exit for the next 600 ms. C, F, Lateral component of the maximum hand velocity after the VP; **p < 0.001, *p < 0.01.
- Figure 5.
EMG correlates after VP in ShortDwell (A, B, C, D) and LongDwell (E, F, G, H) trials. Each trace represents mean across subjects. A, B, E, F, CW perturbation, C, D, G, H, CCW perturbation. All EMG traces were aligned at the time of the VP exit (dark brown line), the “0 ms” in the horizontal axis indicates the timing of the VP exit. FF on (VPs/lFFon, light shade) and off conditions (VPs/lFFoff, dark shade) were compared with VP baseline trials. The dotted oval shape represented higher activation in antagonist muscle; 100-ms time window before VP exit was highlighted in dotted square boxes.
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