In a subset of 13 patients we have previously reported beta band coherence between STN and ipsilateral motor cortical areas (Litvak et al., 2011a). Here we investigated whether the phase of beta band oscillations in the motor cortex was coupled to the amplitude of HFO in the STN in these patients. We included cases who showed significant coherence with ipsilateral motor areas (cases 2–7, 9–13, 15 and 16 in Supplementary Table S1). For each subject and STN channel, we selected the MNI location of peak coherence and extracted the source time series for this location using a beamforming approach. This has been shown to successfully eliminate artefacts originating from the percutaneous DBS electrode wires (Litvak et al., 2010). A single-shell head model was used to compute the lead fields for the forward model (Nolte, 2003). These were constructed based on the subject’s preoperative MRI image that was normalised to a canonical template MRI scan. Raw time series were band-pass filtered between 5 and 35 Hz prior to computation of the covariance matrix. As explained in (Litvak et al., 2011a) we
