The subthalamic nucleus (STN) occupies a strategic position in the motor
network, slowing down responses in situations with conflicting perceptual
input. Recent evidence suggests a role of the STN in emotion processing
through strong connections with emotion recognition structures. As deep brain
stimulation (DBS) of the STN in patients with Parkinson’s disease (PD)
inhibits monitoring of perceptual and value-based conflict, STN DBS may also
interfere with emotional conflict processing. To assess a possible
interference of STN DBS with emotional conflict processing, we used an
emotional Stroop paradigm. Subjects categorized face stimuli according to
their emotional expression while ignoring emotionally congruent or incongruent
superimposed word labels. Eleven PD patients ON and OFF STN DBS and eleven
age-matched healthy subjects conducted the task. We found conflict-induced
response slowing in healthy controls and PD patients OFF DBS, but not ON DBS,
suggesting STN DBS to decrease adaptation to within-trial conflict. OFF DBS,
patients showed more conflict-induced slowing for negative conflict stimuli,
which was diminished by STN DBS. Computational modelling of STN influence on
conflict adaptation disclosed DBS to interfere via increased baseline
activity
