New methods of minimally invasive brain modulation as therapies in psychiatry: TMS, MST, VNS and DBS.

Over the past 20 years, new methods have been developed that have allowed scientists to visualize the human brain in action. Initially positron emission tomography (PET) and now functional magnetic resonance imaging (fMRI) are causing a paradigm shift in psychiatry and the neurosciences. Psychiatry is abandoning the pharmacological model of 'brain as soup', used for much of the past 20 years. Instead, there is new realization that both normal and abnormal behavior arise from chemical processes that occur within parallel distributed networks in specific brain regions. Many of these pathological circuits are becoming well characterized, in disorders ranging from Parkinson's disease, to obsessive-compulsive disorder, to depression. Most recently, there has been an explosion of new techniques that allow for direct stimulation of these brain circuits, without the need for open craniotomy and neurosurgical ablation. The techniques include transcranial magnetic stimulation (TMS), magnetic seizure therapy (MST), vagus nerve stimulation (VNS), and deep brain stimulation (DBS). This review will describe these new tools, and overview their current and future potential for research and clinical neuropsychiatric use. The psychiatry of the future will be better grounded in a firm understanding of neuroanatomy and neurophysiology (as well as pharmacology). These brain stimulation tools, or their next iterations, will play an ever-larger role in clinical neuropsychiatric practice.