Case Studies in Neuroscience: The electrophysiology of a human obsession in nucleus accumbens

Microelectrode recordings were performed during awake deep brain stimulation surgery for obsessive-compulsive disorder, revealing robust brain oscillations that were plainly visible throughout the ventral striatum. There was an elegant topological correspondence between each oscillation and the underlying brain anatomy, most prominently a ~35-Hz gamma-oscillation specific to the nucleus accumbens. Direct provocation of the patient's contamination obsession modulated both firing rate and gamma-oscillation amplitude within the nucleus accumbens. NEW & NOTEWORTHY Surgical implantation of deep brain stimulating electrodes (DBS) to treat obsessive-compulsive disorder (OCD) is an option for patients who have not fully responded to medical intervention or cognitive behavioral therapy. We measured the electrophysiology of a collection of deep brain structures during awake DBS surgery for an OCD patient with an obsession about cleanliness and contamination. The anatomic delineation of these deep brain structures was revealed by distinct brain rhythms, most notably a ~35 Hz oscillation specific to the nucleus accumbens. In the first ever measurement of a human obsessive thought, we found that this ~35-Hz biomarker, as well as the local neuronal action potential rate, were modulated by handing the patient a toothbrush to bring to his face and instructing him to "imagine brushing your teeth with this dirty toothbrush."