(A) STN spikes of recordings with significant gamma coupling (n = 11 units from seven patients [n = 6: one unit, n = 1: five units]) coincided with cortical gamma phases that were on average nearly opposite when comparing contra- and ipsilateral gripping (mean offset = −2.6 rad, 95% CI = [−3.9,–1.4]). (B) When including more recordings (all recordings where PPC > 0, n = 23 from 12 patients [n = 7: one unit, n = 1: two units, n = 3: three units, n = 1: five units]), the offset was very close to 180° (mean offset = 3.1 rad, 95% CI = [2.1, 4.0]). The gamma phase was extracted from ECoG sites that showed the highest coupling during contralateral gripping, as also used for Figures 3–5. (C) P-values derived from a V-test assessing directionality towards an offset of 180° (n = 23) show that the effect of the offset is strongest in a 500 ms sliding window centred around 0.15 s after movement onset, i.e. in a window −0.1–0.4 s around movement onset.