title: Deep Brain Stimulation: More Complex than the Inhibition of Cells and Excitation of Fibers.
abstract: High-frequency deep brain stimulation (DBS) is an effective treatment for some movement disorders. Though mechanisms underlying DBS are still unclear, commonly accepted theories include a "functional inhibition" of neuronal cell bodies and the excitation of axonal projections near the electrodes. It is becoming clear, however, that the paradoxical dissociation "local inhibition" and "distant excitation" is far more complex than initially thought. Despite an initial increase in neuronal activity following stimulation, cells are often unable to maintain normal ionic concentrations, particularly those of sodium and potassium. Based on currently available evidence, we proposed an alternative hypothesis. Increased extracellular concentrations of potassium during DBS may change the dynamics of both cells and axons, contributing not only to the intermittent excitation and inhibition of these elements but also to interrupt abnormal pathological activity. In this article, we review mechanisms through which high extracellular potassium may mediate some of the effects of DBS.
authors.affiliation: Division of Functional Neurosurgery, Department of Neurology, Hospital das Clínicas, School of Medicine of the University of São Paulo, São Paulo, SP, Brazil Department of Radiology and Oncology, School of Medicine of the University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Gerson
authors.initials: G
authors.lastname: Florence
authors.affiliation: Department of Radiology and Oncology, School of Medicine of the University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Koichi
authors.initials: K
authors.lastname: Sameshima
authors.affiliation: Division of Functional Neurosurgery, Department of Neurology, Hospital das Clínicas, School of Medicine of the University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Erich T
authors.initials: ET
authors.lastname: Fonoff
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada Behavioural Neurobiology Laboratory and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada Clement.Hamani@camh.ca.
authors.forename: Clement
authors.initials: C
authors.lastname: Hamani
mesh_terms: D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000502:physiology; D001921:Brain / Q000502:physiology*; D000071080:Cortical Excitability; D046690:Deep Brain Stimulation; D006801:Humans; D009431:Neural Conduction; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology*; D011188:Potassium / Q000502:physiology
chemical_list: D011188:Potassium
keywords: Parkinson’s disease; axon; deep brain stimulation; depolarization block; neuron; potassium