Table 6.
Changes in brain activation relating to neurophysiological parameters
| Talairach coordinates in MNI space |
Correlation analysis |
|||||
|---|---|---|---|---|---|---|
| Region | Side | x | y | z | Z-value | (r2) |
| (i) BG and IHI40c | ||||||
| Primary motor cortex | I | 40 | −20 | 58 | 4.32* | (+) 0.63 |
| I | 42 | −18 | 50 | 4.22* | (+) 0.60 | |
| Supplementary motor area | I | 12 | −12 | 58 | 4.39* | (+) 0.62 |
| (ii) BF and IHI40c | ||||||
| Primary motor cortex | I | 44 | −20 | 64 | 4.03* | (+) 0.49 |
| (iii) BG and I50‡ | ||||||
| Dorsolateral | C | 42 | 8 | 52 | 4.42 | (+) 0.56 |
| premotor cortex | ||||||
| Ventrolateral premotor | C | −44 | 12 | 20 | 4.19 | (+) 0.53 |
| cortex/BA44 | I | 46 | 14 | 24 | 4.65 | (+) 0.60 |
| Pre-supplementary motor area |
I | 2 | 20 | 50 | 4.87 | (+) 0.63 |
| Frontal operculum | I | −34 | 20 | 0 | 4.34 | (+) 0.55 |
| Cerebellum | C | −38 | −62 | −50 | 4.81 | (+) 0.63 |
| (iv) BF and I50 * | ||||||
| Ventrolateral premotor | C | −46 | 22 | 20 | 3.55 | (+) 0.41 |
| cortex/BA44 | C | −52 | 20 | 26 | 3.38 | (+) 0.39 |
| I | 48 | 20 | 26 | 3.2 | (+) 0.35 | |
IHI40c reflects the change seen in the interhemispheric inhibition targeting the non-dominant motor cortex when the dominant hand is active, at an ISI of 40 ms. A higher value for IHI40c represents less transcallosal inhibition. I50 is the stimulation intensity required to get a response of 50% of the maximum MEP. A higher value for I50 indicates lower motor cortex excitability.
Voxels are significant at P<0.05, corrected for multiple comparisons within a priori ROIs (see Methods section).
Clusters are significant at P<0.05, corrected for multiple comparisons across whole brain. The direction of the correlation (+ or −) is given next to the value for the coefficient of determination, r2.
C = contralateral, I = ipsilateral to hand movement, BA=Brodmann area, BG=parameter estimate for the main effect of hand grip, BF=parameter estimate for the force covariate (see Methods section).