Table E.2.

Regions and corresponding spatial filters used to check the spatial specificity of our results: Two Hjorth montages were used for checking the premotor cortex: One, more posterior and broader, centered on the FC3/FC4 electrode, and one, more anterior and narrower, centered on the F3/F4 electrode. Note that O1/O2 is at the very edge of the cap, thus there is no electrode caudal of O1/O2. We have therefore opted for a partial Hjorth montage around these electrodes. The C3/C4-Hjorth spatial filters are given for completeness.

Area	Ipsilateral (left)	Contralateral (right)
Primary motor cortex	$\mathrm{C3}-\frac{1}{4}(\mathrm{FC1}+\mathrm{FC5}+\mathrm{CP1}+\mathrm{CP5})$	$\mathrm{C4}-\frac{1}{4}(\mathrm{FC2}+\mathrm{FC6}+\mathrm{CP2}+\mathrm{CP6})$
Premotor cortex	$\mathrm{FC3}-\frac{1}{4}(\mathrm{F1}+\mathrm{F5}+\mathrm{C1}+\mathrm{C5})$	$\mathrm{FC4}-\frac{1}{4}(\mathrm{F2}+\mathrm{F6}+\mathrm{C2}+\mathrm{C6})$
	$\mathrm{F3}-\frac{1}{4}(\mathrm{AF3}+\mathrm{F1}+\mathrm{F5}+\mathrm{FC3})$	$\mathrm{F4}-\frac{1}{4}(\mathrm{AF4}+\mathrm{F2}+\mathrm{F6}+\mathrm{FC4})$
Occipital cortex	$\mathrm{O1}-\frac{1}{3}(\mathrm{PO3}+\mathrm{PO7}+\mathrm{Oz})$	$\mathrm{O2}-\frac{1}{3}(\mathrm{PO4}+\mathrm{PO8}+\mathrm{Oz})$