Table 4.
TMS measures of corticospinal excitability
| Mean (range) | Correlation with age2 (r2) |
|
|---|---|---|
| 1. Motor thresholds (% stimulator’s intensity) | ||
| Left M1 | ||
| Resting (RMT) | 37.7 (28–65) | ns |
| Active (AMT) | 28.4 (19–45) | ns |
| Right M1 | ||
| Resting (RMT) | 36.5 (29–50) | ns |
| Active (AMT) | 28 (22–39) | ns |
| 2. RC of active MEP amplitude‡ (CMAP corrected) | ||
| AUC | 12.1 (1.8–23) | (−) 0.42* |
| Parameter estimates (Boltzmann model) | ||
| MEPmax/CMAP | 0.39 (0.03–0.82) | ns |
| I50 (%AMT) | 137 (115–168) | ns |
| 1/ slope | 0.14 (0.05–0.37) | ns |
The direction of the correlation (+ or −) is given next to the value for the coefficient of determination, (r2).
‡
refers to stimulation of left M1
*
P<0.05.
RMT=resting motor threshold; AMT=active motor threshold; RC recruitment curves; CMAP=compound motor action potential; AUC=area under the curve; MEPmax=maximum MEP amplitude estimated; I50 = stimulation intensity needed to get a response of 50% of the maximal MEP.