Conclusions
oculomotor impulsivity, PD
In summary, a combined approach of eye-tracking and high-density EEG allowed us to differentiate the effects of two commonly used STN-DBS frequencies on response inhibition in the antisaccade task and to explore their cortical correlates. While the latency of correct antisaccades was reduced by 130 Hz and 60 Hz pulse frequencies alike, the latency of reflexive errors increased under both DBS conditions. Thus, our preliminary results do not support a general association of STN-DBS with oculomotor impulsivity. Instead, STN-DBS may promote voluntary actions at the expense of slower reflexive responses.The probability for impulsive errors decreased exclusively with 60 Hz-DBS. As the effect size was small, it remains to be determined whether this potentially beneficial effect of mid-frequency DBS on response inhibition is reproducible and clinically relevant.Only 130 Hz-DBS reversed the relationship between preparatory midfrontal theta activity and antisaccade latency in comparison with DBS off-state in a trial-wise analysis. Sixty Hz-DBS, on the other hand, was associated with an increase in preparatory midfrontal theta power compared with the off-DBS state which may be interpreted as a correlate for enhanced cognitive control. Hence, our results warrant future studies on the cognitive effects of mid-frequency STN-DBS in PD. Since high and mid-frequency STN-DBS may thus differentially modulate response inhibition capacity, pulse frequency needs to be considered when interpreting inconclusive results of previous and upcoming studies on the effects of STN-DBS on cognitive control.