Deep-brain electrical stimulation (DBS) can provide substantial motor benefit and impact non-motor domains of cognition and mood in Parkinson disease (PD) when implanted in the subthalamic nucleus (STN). However, the neural mechanisms underlying these effects are not fully understood. We are collaborating with the Culver Lab to use high density diffuse optical tomography (HD-DOT) to understand how STN DBS alters functional cortical networks in the brain.