Neurophysiology recordings will be performed from dorsolateral prefrontal cortex (DLPFC) during deep brain stimulation surgery, with and without STN or GPI stimulation, at rest and during a working memory task.

Neurophysiology recordings will be performed from subthalamic nucleus (STN) or globus pallidus internus (GPI) with stimulation on and off, at rest and during a working memory task, in patients who have previously been implanted with DBS and have implantable pulse generators capable of recording local field potentials.

Neural activities from the dorsolateral prefrontal cortex and implanted DBS generator will be recorded, during resting and working memory tasks, and with the DBS target turned on and off.

Working memory tasked will be conducted during surgery, and local field potentials (LFPs) will be recorded from the DLPFC both at rest and during task execution, under two conditions: with and without stimulation.

Local field potentials will be recorded from subthalamic nucleus or globus pallidus internus in patients with an existing DBS system with implantable pulse generator capable of recording local field potentials. Recordings will be performed at rest and during a working memory task, with DBS on and off.