Table 1.
Experiment overview
| Experiment | Number of subjects incl. (recruited), subject type | Mean age ± SD [range] | Gender F, M | Technique | Task | Experimental aim | Relevant figures and tables |
|---|---|---|---|---|---|---|---|
| Experiment 1, AO | 31 (35) healthy | 23 ± 4 [19–40] | 21, 10 | fMRI | Action observation | Localize cerebellar voxels responding to action observation | Fig. 2, Tables 2 and 3, Supplementary Figs 1, 2, 6 and 7, Supplementary Tables 1–4 |
| Experiment 2, AOrep1 | 25a (25) healthy | 25.2 ± 4 [19–32] | 13, 12 | fMRI | Action observation | Replicability of cerebellar activations to action observation | Fig. 2, Tables 2 and 3, Supplementary Figs 1, 2, 6 and Supplementary Tables 1–4 |
| Experiment 3, AOrep2 | 23 (23) healthy | 25.5 ± 3.6 [21–33] | 11, 12 | fMRI | Action observation | Replicability of cerebellar activations to action observation | Fig. 2, Tables 2 and 3, Supplementary Figs 1, 2, 6 and 7, Supplementary Tables 1–4 |
| Experiment 4, WD | 25a (25) healthy | 25.2 ± 4 [19–32] | 13, 12 | fMRI | Weight estimation | Localize cerebellar activations to the weight discrimination task and compare them with Experiments 1–3 | Fig. 3, Supplementary Table 4 and Supplementary Fig. 5 |
| Experiment 5, SCA6 | 19WD, and 17SARA (21) SCA6 | 62 ± 7 [49–80] 60.8 ± 7 [49–68] | WD 14, 5 SARA 12, 5 Total 15, 6 | Behav + eye tracking (n = 4) | Weight estimation | Investigate whether cerebellar deficits are reflected in decreased accuracy in perception | Fig. 4 and Supplementary Fig. 3 |
| 31 healthy | 61 ± 7 [43–74] | 15, 16 | Behav + eye tracking (n = 7) | Weight estimation | |||
| Experiment 6, EMG | 10 healthy | 32.5 ± 4.3 [29, 42] | 4, 6 | FDI EMG | Action observation | Identify whether stronger EMG activity during ActionOBS could explain brain activity in motor regions | Supplementary Fig. 4 |
| Experiment 7, fMRI | 7 (7) healthy | 26 ± 4.5 [21–33] | 5, 2 | fMRI | Action observation and eye movements | Test whether differences in eye movements between ActionOBS and CtrlOBS alone could explain the stronger activity for ActionOBS | Supplementary Fig. 6 |
All groups of participants are independent except athose in which the same 25 participants underwent both the passive observation and the weight estimation task in separate sessions. In Experiment 1, four participants were excluded from the statistical analysis: two due to excessive head motion (displacement of >3.5 mm voxel dimension), one reported sleepiness, and one because of image distortion. In Experiment 5, two participants were excluded from the weight lifting task because pre-symptomatic, and two more were excluded from the correlation with SARA because they did not have SARA scores. Experiments 6 and 7 are control experiments aimed at addressing some possible confounds. AO = action observation; AOrep = action observation replication; FDI = first dorsal interosseous; fMRI = functional MRI; WD = weight discrimination.