Figure 2.

Effect of notch filters to suppress power line and DBS related artefacts. (A) Power spectrum of left PPN-LFP at base line (black line) with a simulated strong 130 Hz artefact (red line) superimposed. After notch filtering at 50 Hz and 130 Hz, the corresponding components are suppressed (blue line), the additional peak at 128 reflects environmental noise generated by surrounding medical equipment; (B) The difference of the DIT in the two directions (i.e., DITD = DIT (PPN_L → PPN_R*) − DIT (PPN_R* → PPN_L*)). Blue: DITD between the PPN-LFPs (without the simulated 130 Hz artefact) after notch filtering (50 Hz, 130 Hz). Red: DITD between the PPN-LFPs (both including superimposed simulated 130 Hz artefacts of equal strength) after notch filtering (50 Hz, 130 Hz). Abbreviations: DBS: deep brain stimulation, DIT: directed information transfer, LFP: local field potentials, PPN: pedunculopontine nucleus region (_L = left, _R = right, * denotes clinically more affected side).