Erik Middlebrooks
During the 21st century, our understanding of the human brain has exponentially grown, in part driven by the field of brain connectomics. Using this technology, we continue to understand more and more about normal and abnormal brain circuits that have greatly enhanced our understanding of many neurologic disorders. Through this framework, we have a greater appreciation of many diseases being network-based abnormalities rather than traditional localizationist ideas that have failed to produce consolidated and accurate theories of pathophysiology. As our understanding increases, one of the most promising tools available to target these network disturbances is brain neuromodulation.
Although neuromodulation is not an entirely new technology, our understanding of its mechanism and role in treating diseases continues to grow and has recently been aided by the application of connectomics. In my opinion, the next most widely adopted use of connectomics in clinical application is in the realm of neuromodulation. Many studies have now unequivocally shown its role in enhancing targeting and programming in deep brain stimulation (DBS), as well as its potential to unravel new targets and consolidate outstanding mysteries and debates in traditional targets. In this review, we discuss the functional anatomy and physiology relevant to the most common and approved applications of clinical DBS to provide the reader an introduction to the application of connectomics to clinical DBS.
Some important highlights include the use of connectomics to consolidate decades-old debates on the structural target for treating tremor, which all can be explained by association with a single white matter tract. We also show how connectomics can explain a single theory/network underlying multiple described targets in obsessive-compulsive disorder (OCD). Additionally, we discuss how connectomics can be applied to understand the mechanism of action and improve targeting in deep brain stimulation for epilepsy, the most recently approved use of DBS. We also discuss the connectomic anatomy that underpins the treatment of Parkinson disease and may explain ideal “sweet spots” within the most common targets of the subthalamic nucleus and globus pallidus internus.