Summary of findings
PD
In this study, we aimed at investigating the effects of high- and mid-frequency STN-DBS on response inhibition in patients with PD using the antisaccade task in combination with EEG recordings. Against our a priori hypothesis, our behavioral findings did not support that high-frequency STN-DBS leads to a higher probability of impulsive actions in the antisaccade task in PD. Sixty Hz-DBS may even have a beneficial effect on response inhibition as it was related to a higher accuracy in the antisaccade task compared with both off-DBS state and high-frequency stimulation.While no significant differences in mid- or lateral prefrontal brain activity emerged between the 60 Hz and 130 Hz conditions in the time–frequency domain analysis of the EEG data, comparison with DBS off-state revealed that 60 Hz-DBS may be associated with an increase in midfrontal theta band power during the pre-stimulus period. In off-DBS state, higher midfrontal theta activity was associated with longer antisaccade latency in a trial-wise analysis. This relationship was reversed by 130 Hz-DBS, indicating that theta-based preparatory activity may be modulated by high frequency STN-DBS.Switching on STN-DBS had opposing effects on the latency of correctly executed antisaccades and erroneous reflexive saccades regardless of pulse frequency. While antisaccade latency decreased, the latency for directional errors towards the visual stimulus increased in both DBS conditions. During the preparatory period before stimulus presentation, high- and mid-frequency STN-DBS both induced a decrease of midfrontal beta power compared with off-DBS state.