Brain Stimulation for Neurological and Psychiatric Disorders, Current Status and Future Direction

Abstract

Interest in brain stimulation therapies has been rejuvenated over the last decade and brain stimulation therapy has become an alternative treatment for many neurological and psychiatric disorders, including Parkinson's disease (PD), dystonia, pain, epilepsy, depression, and schizophrenia. The effects of brain stimulation on PD are well described, and this treatment has been widely used for such conditions worldwide. Treatments for other conditions are still in experimental stages and large-scale, well controlled studies are needed to refine the treatment procedures. In the treatment of intractable brain disorders, brain stimulation, especially transcranial magnetic stimulation (TMS), is an attractive alternative to surgical lesioning as it is relatively safe, reversible, and flexible. Brain stimulation, delivered either via deeply implanted electrodes or from a surface-mounted transcranial magnetic device, can alter abnormal neural circuits underlying brain disorders. The neural mechanisms mediating the beneficial effects of brain stimulation, however, are poorly understood. Conflicting theories and experimental data have been presented. It seems that the action of stimulation on brain circuitry is not limited to simple excitation or inhibition. Alterations of neural firing patterns and long-term effects on neurotransmitter and receptor systems may also play important roles in the therapeutic effects of brain stimulation. Future research on both the basic and clinical fronts will deepen our understanding of how brain stimulation works. Realtime computation of neural activity allows for integration of brain stimulation signals into ongoing neural processing. In this way abnormal circuit activity can be adjusted by optimal therapeutic brain stimulation paradigms.The modern era of brain stimulation treatment started in the 1950s with an early application of deep brain stimulation (DBS) to treat patients with intractable pain. Interest in DBS as a treatment for movement disorders has surged since the late 1980s. With the development of new devices such as transcranial magnetic stimulators and refinements in DBS paradigms, brain stimulation has been gradually replacing surgical ablation as a uniquely promising clinical procedure for the treatment of many neurological disorders that are unresponsive to existing therapies. Movement DisordersParkinson's Disease. Although pharmacological dopamine (DA) enhancement has therapeutic benefits for PD, long-term use also produces the undesirable side effect of dyskinesia. Surgical ablation and DBS were explored during the 1970s and 1980s. Benabid et al. (1987) reported that high-frequency stimulation of the ventral intermediate thalamic nucleus can suppress the tremor syndrome of PD. During the following decade, we witnessed tremendous interest and great success of DBS treatments in PD.Currently, the major targets of DBS for PD treatment are the subthalamic nucleus (STN) and the internal segment of globus pallidus (GPi) within the thalamocortical basal ganglia pathways....

Striatal projections of the vagal‐responsive region of the thalamic parafascicular nucleus in macaque monkeys

“…Based on this observation, chronic vagus nerve stimulation (VNS) with an implanted electrode and stimulator (for review see Schachter and Schmidt, 2004) is employed for intractable epilepsy. Independently, another stimulation therapy, deep brain stimulation (DBS), is also used clinically for treating epilepsy (Chang, 2004;Theodore and Fisher, 2004). With the underlying mechanisms remaining unknown, these two methods have been studied separately.…”

Neuropsychological Considerations for Parkinson’s Disease Patients Being Considered for Surgical Intervention with Deep Brain Stimulation

“…It has been suggested that STN-DBS affects neuronal membrane potentials and voltage-dependent calcium channels surrounding the pathologic circuitry [ 9 ] . In doing so, DBS may be altering the fi ring pattern of STN neurons to immediately produce a therapeutic effect at the electrode's tip [ 42,43 ] . It is also possible that the stimulation is not affecting the cell bodies; rather, the axons carrying signals into the STN from other areas may be the target of the stimulation's effects [ 9 ] .…”

“…More recently, DBS has been used to treat endogenous depression [ 42 ] . Like PD, major depressive disorder (MDD) was initially treated using ablative surgeries until monoamine oxidase inhibitors and tricyclic antidepressants were found to effectively improve depressive symptoms [ 125 ] .…”

Linking brain dynamics, neural mechanisms, and deep brain stimulation in Parkinson's disease: An integrated perspective

“…The latter procedure is not limited to PD, and is also used to treat disorders such as dystonia, pain, depression, and obsessive compulsive disorders [11]. Intriguingly, both electrical stimulation and the lesion of motor targets in the basal ganglia appear to reverse movement abnormalities such as tremor, without any obvious deleterious effects on other aspects of movements [12].…”