Subthalamic Nucleus Deep Brain Stimulation: Basic Concepts and Novel Perspectives

Abstract

Over the last decades, extensive basic and clinical knowledge has been acquired on the use of subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson’s disease (PD). It is now clear that mechanisms involved in the effects of this therapy are far more complex than previously anticipated. At frequencies commonly used in clinical practice, neural elements may be excited or inhibited and novel dynamic states of equilibrium are reached. Electrode contacts used for chronic DBS in Parkinson’s disease are placed near the dorsal border of the nucleus, a highly cellular region. DBS may thus exert its effects by modulating these cells, hyperdirect projections from motor cortical areas, afferent and efferent fibers to the motor STN. Advancements in neuroimaging techniques may allow us to identify these neural elements, optimizing surgical targeting. In this review we provide an update on mechanisms and the neural elements modulated by STN DBS.

Significance Statement Over the last decades, extensive basic and clinical knowledge has been acquired on the use of subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson’s disease (PD). It is becoming clear that DBS exerts its effects through several mechanisms and influences various neural structures and circuits. In this article, we discuss electrophysiological findings suggesting that stimulation not only modulates activity of neural elements but also leads to novel dynamic states of equilibrium. We also present anatomic data showing that the STN is not a homogeneous structure and review fiber pathways and regions of the nucleus potentially modulated by DBS. Finally, we discuss novel neuroimaging modalities and how these may be used to optimize technical aspects of the surgery.