Future Of Brain Stimulation Research Articles

Future of brain stimulation: New targets, new indications, new technology

In the last quarter of a century, DBS has become an established neurosurgical treatment for Parkinson's disease (PD), dystonia, and tremors. Improved understanding of brain circuitries and their involvement in various neurological and psychiatric illnesses, coupled with the safety of DBS and its exquisite role as a tool for ethical study of the human brain, have unlocked new opportunities for this technology, both for future therapies and in research. Serendipitous discoveries and advances in structural and functional imaging are providing abundant "new" brain targets for an ever-increasing number of pathologies, leading to investigations of DBS in diverse neurological, psychiatric, behavioral, and cognitive conditions. Trials and "proof of concept" studies of DBS are underway in pain, epilepsy, tinnitus, OCD, depression, and Gilles de la Tourette syndrome, as well as in eating disorders, addiction, cognitive decline, consciousness, and autonomic states. In parallel, ongoing technological development will provide pulse generators with longer battery longevity, segmental electrode designs allowing a current steering, and the possibility to deliver "on-demand" stimulation based on closed-loop concepts. The future of brain stimulation is certainly promising, especially for movement disorders-that will remain the main indication for DBS for the foreseeable future-and probably for some psychiatric disorders. However, brain stimulation as a technique may be at risk of gliding down a slippery slope: Some reports indicate a disturbing trend with suggestions that future DBS may be proposed for enhancement of memory in healthy people, or as a tool for "treatment" of "antisocial behavior" and for improving "morality."

Brain stimulation in psychiatry and its effects on cognition

From the advent of electroconvulsive therapy in the 1930s to the emergence of magnetic seizure therapy in the 2000s, the refinement of brain stimulation in psychiatry has been largely motivated by a desire to achieve clinical efficacy and eliminate cognitive adverse effects. As a result of these efforts, a clinically efficacious brain stimulation technique that does not negatively affect cognition could soon be available. In the course of developing a 'cognitively safe' brain stimulation technique, potential methods to enhance various aspects of cognition have also emerged. In this article, we discuss the past, present and future of brain stimulation in psychiatry, and its effects on cognition.

Past, Present and Future of Brain Stimulation

Recent technological advances including brain imaging (higher resolution in space and time), miniaturization of integrated circuits (nanotechnologies), and acceleration of computation speed (Moore’s Law), combined with interpenetration between neuroscience, mathematics, and physics have led to the development of more biologically plausible computational models and novel therapeutic strategies. Today, mathematical models of irreversible medical conditions such as Parkinson’s disease (PD) are developed and parameterised based on clinical data. How do these evolutions have a bearing on deep brain stimulation (DBS) of patients with PD? We review how the idea of DBS, a standard therapeutic strategy used to attenuate neurological symptoms (motor, psychiatric), has emerged from past experimental and clinical observations, and present how, over the last decade, computational models based on different approaches (phase oscillator models, spiking neuron network models, population-based models) have started to shed light onto DBS mechanisms. Finally, we explore a new mathematical modelling approach based on neural field equations to optimize mechanisms of brain stimulation and achieve finer control of targeted neuronal populations. We conclude that neuroscience and mathematics are crucial partners in exploring brain stimulation and this partnership should also include other domains such as signal processing, control theory and ethics.

Future prospects of brain stimlation

Chronic high frequency (130 Hz) stimulation (HFS) of the thalamic target Vim has replaced thalamotomy as a treatment of tremor of various origins and was extended to two other targets (Subthalamic nucleus (STN) and the medial pallidus (CPO), since 1993 based on recent experimental data in rats and monkeys. STN appears to be a target of major interest, able to control the three cardinal symptoms and to allow the decrease or suppression of levodopa treatment, which then suppresses also levodopa induced dyskinesias. The mechanisms of action of HFS are not fully understood, but are definitely related to high frequency and are probably different depending on the target. Inhibition of cellular activity or of network functions could be induced, by jamming ofa retroactive loop for tremor, or by shutdown ofneurotransmitter release in STN. All cardinal symptoms are alleviated from tremor to akinesia and rigidity. The effects remain stable over more than five years chronic HFS of STN, as the method of choice when a surgical procedure is indicated for the treatment of Parkinson!s disease and even more when a bilateral procedure is necessary. Recent data show that STN stimulation could be useful in the treatment of dystonia as well as some forms of epilepsies. It is therefore possible that OAS in STN as well as in other targets could become a potent therapeutic tool in the future for neurological disorders. The future of brain stimulation will depend on new technologies (new circuits, electrodes, web based programmers), waveforms (alternatives to square waves, random distribution), targets (hypothalamic nuclei, locus coeruleus) and indications (dystonia, epilepsy, eating disorders). [Neural Res 2000; 22: 237-246]