Table I.
Per‐subject M1 depths
| Subject | M1 depth (mm)* | Threshold (E, V/m)** | 125% MT (E, V/m)** | |
|---|---|---|---|---|
| Voluntary | TMS | |||
| 1246 | 38 | 37 | 70 | 87 |
| 1265 | 26 | 28 | 77 | 96 |
| 1280 | 37 | 40 | 59 | 73 |
| 1281 | 27 | 24 | 100 | 125 |
| 1286 | 31 | 33 | 54 | 66 |
| 1316 | 22 | 22 | 109 | 137 |
| 1355 | 29 | 34 | 59 | 73 |
| Mean | 29.9 | 31.2 | 79.2 | 94.1 |
*
Depth (in mm) from scalp surface to center‐of‐mass of M1 activation induced by movement of the right index finger (voluntary) and by transcranial magnetic stimulation (TMS) eliciting movement of the right first dossal interosseous muscle (FDI). The two distances did not differ significantly but did covary significantly (r = 0.93; Fig. 4).
**
Absolute E field values at the response site for stimulation at motor threshold and at 125% of motor threshold (MT) were computed in volts per meter (V/m) using a 3D computer model of the E field created by the Cadwell coil scaled by the machine setting (% output) and the distance from the scalp.