The concomitant stimulation of the subthalamic nucleus and the substantia nigra pars reticulata is a promising approach to improve treatment of refractory axial symptoms in Parkinson's disease. While dual stimulation of the subthalamic nucleus and the substantia nigra pars reticulata has previously shown beneficial effects on gait, the role of the substantia nigra, a crucial component of the basal ganglia circuitry, in cognitive functions such as attention and executive control remains underexplored. This study aimed to investigate the impact of selective substantia nigra pars reticulata stimulation on attentional performance in patients receiving standard deep brain stimulation of the subthalamic nucleus.

Twelve patients with bilateral subthalamic nucleus stimulation underwent computerized assessment of attention using a simple reaction time task. Reaction times were assessed under standard stimulation of the subthalamic nucleus versus simultaneous stimulation of the subthalamic nucleus and the substantia nigra pars reticulata.

The results revealed a significant improvement in reaction times during the simple reaction time task when patients received dual stimulation compared to standard stimulation.

Our findings provide further evidence for the pivotal role of the substantia nigra pars reticulata in cognitive functions such as attention. Despite the limitations of the study, including a small sample size, our results suggest potential benefits of simultaneous deep brain stimulation of the subthalamic nucleus and the substantia nigra pars reticulata on attentional performance in patients with Parkinson's disease. Further research with larger cohorts is warranted to confirm these findings and better understand the underlying mechanisms.