Fig. 1.

Stimulation settings and experimental paradigm. A. Schematic illustration of the electrode configuration. DBS was applied to one of the two middle contacts (E1 or E2) and LFPs were recorded bipolarly from the two adjacent contacts (E0 and E2 or E1 and E3). Bipolar contacts were recorded directly and not recovered off-line. B. Time-frequency spectrogram of first three DBS blocks in patient 1. During stimulation the finely-tuned gamma (FTG) arises (label 1) and then outlasts DBS (label 2) when it increases in frequency. In addition, beta suppression is evident during DBS (label 3). DBS blocks at 130 Hz are denoted by the grey bars at the top of the trace. Note that line noise artefacts were present throughout the recording at 50 Hz along with the DBS subharmonic at 65 Hz but are reduced by second-order IIR notch filters. C. DBS-induced narrowband artefacts at a subharmonic DBS frequency (65 Hz; label 4) or due to an aliasing phenomenon (80 Hz; label 5). Time-frequency spectrum shown for block 2 of patient 1with DBS at 130 Hz and before applying IIR notch filters (see Methods). The grey bar and vertical lines denote DBS onset and offset. The FTG feature is contoured (see Methods). Note that DBS-induced artefacts do not change in frequency throughout stimulation and cease immediately after DBS is stopped. D. Representative time-frequency spectrogram from patient 3 block 2. Apart from the FTG after DBS (label 6) we observe a low-gamma rebound (label 7) which appears after DBS is stopped with a slight delay, spans from 50 to 70 Hz and lasts for several seconds.