Mechanisms of action of deep brain stimulation for the treatment of psychiatric disorders

Deep brain stimulation (DBS) has recently emerged as a potential treatment for medically intractable psychiatric disease. Pilot clinical studies have been performed with DBS of the subcallosal cingulate (SCC) white matter and ventral anterior internal capsule/ventral striatum (VC/VS) for the treatment of depression and obsessive–compulsive disorder with encouraging results. However, little is known about the underlying neural response and network activity generated when DBS is applied to these targets. This chapter summarizes the current understanding of the axonal response to DBS, and discusses the general network architectures believed to underlie psychiatric disease. We use diffusion tensor imaging tractography to better understand axonal trajectories surrounding DBS electrodes implanted in the SCC and VC/VS. Finally, we attempt to reconcile various data sets by presenting generalized hypotheses on potential therapeutic mechanisms of DBS for the treatment of psychiatric disorders.