More than half a century ago, the field of human stereotactic neurosurgery was borne from the compelling need to treat patients with refractory forms of what we now call psychiatric disorders. In the late 1990s, deep brain stimulation (DBS) joined the therapeutic stage previously occupied solely by stereotactic lesion procedures. Obsessive-compulsive disorder (OCD) is the indication with the most clinical experience with DBS and the only one with a form of approval (via a humanitarian device exemption; HDE) from the US FDA. In the first two decades of this century, progress in DBS for OCD came in the form of a number of studies testing the efficacy of myriad brain targets, largely driven by empiricism. The last few years have witnessed an attempt to weave these narratives into a cohesive story, one that conceives of these potential targets not as isolated islands of disease, but rather as connected nodes in a dysfunctional network [1].

A series of recent papers summarized in Baldermann et al. [2] has attempted to build a parsimonious answer to the question of network targeting in DBS for OCD. They identify the connectomic profile of effective DBS contacts using normative tractography data (i.e., results derived from populations of healthy controls) to identify tracts associated with positive outcome. Their main finding is the prominence of a tract connecting the anterior cingulate cortex (ACC) and the region of the subthalamic nucleus (STN) that courses through the anterior limb of the internal capsule. Notably, all of these regions have been the target of DBS or lesion procedure for OCD, providing circumstantial evidence for their relevance. They suggest that this tract may represent a “hyperdirect” pathway between dACC and ventromedial STN in a manner analogous to the motor hyperdirect pathway that connects motor cortex to dorsolateral STN. This candidate tract was initially identified in outcome data from a single institution and then found to correlate with positive outcomes in datasets from several other institutions across a summed cohort of more than 100 patients.

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