Table 1.
ISP area and background EMG level in the right FDI (mean ±s.d.) in the different experimental conditions
| ISP area (mV ms) | Background EMG level (mV) | |
|---|---|---|
| Different tonic and phasic contractions of the left FDI | ||
| Unilateral isometric contraction of the right FDI | 1.83 ± 0.85* | 0.399 ± 0.120 |
| Bilateral isometric contraction of the FDI | 3.37 ± 1.61 | 0.423 ± 0.121 |
| Isometric contraction of the right FDI and repetitive movements of the left index | 3.27 ± 1.76 | 0.377 ± 0.117*a |
| Isometric contraction of the right FDI and sequential movements of the left index | 4.04 ± 2.60 | 0.377 ± 0.099*a |
| Isometric left FDI contraction at different strength levels | ||
| Unilateral isometric contraction of the right FDI | 2.72 ± 1.77* | 0.424 ± 0.095 |
| Isometric contraction of the right FDI and minimal contraction of the left FDI | 4.27 ± 2.50 | 0.448 ± 0.077 |
| Isometric contraction of the right FDI and maximal contraction of the left FDI | 4.72 ± 2.33 | 0.427 ± 0.064 |
| Imagined movements involving the left FDI | ||
| Unilateral isometric contraction of the right FDI | 2.88 ± 1.92 | 0.435 ± 0.133 |
| Isometric contraction of the right FDI and imagined left thumb-to-index opposition | 3.81 ± 2.59* | 0.425 ± 0.126 |
| Isometric contraction of the right FDI and mental calculation | 2.95 ± 2.35 | 0.418 ± 0.131 |
| Isometric contraction of other muscles (topographical specificity) | ||
| Sub-experiment 1 | ||
| Unilateral isometric contraction of the right FDI | 2.66 ± 1.90 | 0.423 ± 0.063 |
| Bilateral isometric FDI contraction | 4.07 ± 3.00*b | 0.415 ± 0.072 |
| Isometric contraction of the right FDI and the right TA | 2.24 ± 1.16 | 0.420 ± 0.080 |
| Isometric contraction of the right FDI and the left EIP | 4.72 ± 2.54*b | 0.422 ± 0.074 |
| Sub-experiment 2 | ||
| Unilateral isometric contraction of the right FDI | 3.26 ± 2.23 | 0.434 ± 0.127 |
| Isometric contraction of the right FDI and the left TA | 3.52 ± 2.14 | 0.435 ± 0.129 |
| Sub-experiment 3 | ||
| Unilateral isometric contraction of the right FDI | 3.21 ± 1.72 | 0.433 ± 0.146 |
| Isometric contraction of the right FDI and the left ECR | 3.98 ± 1.79 | 0.427 ± 0.106 |
| Isometric contraction of the right FDI and the left BB | 2.57 ± 0.90 | 0.425 ± 0.090 |
| Preparation of left FDI contraction (temporal specificity) | ||
| Unilateral isometric contraction of the right FDI and no RT (baseline) | 2.47 ± 2.07 | 0.376 ± 0.173 |
| Isometric contraction of the right FDI during RT (TMS before the EMG onset in the left FDI) | 2.95 ± 2.42 | 0.380 ± 0.147 |
| Isometric contraction of the right FDI during RT (TMS during the EMG burst in the left FDI) | 4.48 ± 2.45*c | 0.372 ± 0.140 |
ISP, ipsilateral silent period; EMG, electromyographic; FDI, first dorsal interosseous muscle; TA, tibialis anterior muscle; EIP, extensor indicis proprius muscle; ECR, extensor carpi radialis; BB, biceps brachii. *P < 0.05, repeated-measures ANOVA, and post hoc Newman–Keuls multiple comparison tests. aWith respect to bilateral isometric contraction of the FDI. bWith respect to contraction of the right FDI alone or simultaneous isometric contraction of the right FDI and right TA. cWith respect to unilateral isometric contraction of the right FDI and no RT (baseline).