title: Anodal vs cathodal stimulation of motor cortex: a modeling study.
abstract: OBJECTIVE
  To explore the effects of electrical stimulation performed by an anode, a cathode or a bipole positioned over the motor cortex for chronic pain management.
  
  
  METHODS
  A realistic 3D volume conductor model of the human precentral gyrus (motor cortex) was used to calculate the stimulus-induced electrical field. The subsequent response of neural elements in the precentral gyrus and in the anterior wall and lip of the central sulcus was simulated using compartmental neuron models including the axon, soma and dendritic trunk.
  
  
  RESULTS
  While neural elements perpendicular to the electrode surface are preferentially excited by anodal stimulation, cathodal stimulation excites those with a direction component parallel to its surface. When stimulating bipolarly, the excitation of neural elements parallel to the bipole axis is additionally facilitated. The polarity of the contact over the precentral gyrus determines the predominant response. Inclusion of the soma-dendritic model generally reduces the excitation threshold as compared to simple axon model.
  
  
  CONCLUSIONS
  Electrode polarity and electrode position over the precentral gyrus and central sulcus have a large and distinct influence on the response of cortical neural elements to stimuli.
  
  
  CONCLUSIONS
  Modeling studies like this can help to identify the effects of electrical stimulation on cortical neural tissue, elucidate mechanisms of action and ultimately to optimize the therapy.
authors.affiliation: Biomedical Signals and Systems Group, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
authors.forename: Ljubomir
authors.initials: L
authors.lastname: Manola
authors.forename: Jan
authors.initials: J
authors.lastname: Holsheimer
authors.forename: Peter
authors.initials: P
authors.lastname: Veltink
authors.forename: Jan R
authors.initials: JR
authors.lastname: Buitenweg
mesh_terms: D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D003198:Computer Simulation; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D004525:Efferent Pathways / Q000502:physiology; D004599:Electric Stimulation Therapy / Q000379:methods*; D004566:Electrodes / Q000592:standards; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D008959:Models, Neurological; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D059408:Pain Management; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology*