title: The nature and time course of cortical activation following subthalamic stimulation in Parkinson's disease.
abstract: We studied the time course and nature of interactions between the subthalamic nucleus (STN) and the motor cortex in 8 Parkinson disease (PD) patients with chronically implanted STN deep-brain stimulation (DBS) electrodes. We first identified the cortical evoked potentials following STN stimulation. The most consistent potential was positive wave with peak latency of 22.2 +/- 1.2 ms from stimulation of clinically effective contacts. We then stimulated the motor cortex with transcranial magnetic stimulation (TMS) at 2-15 ms and at the latency of the evoked potential ( approximately 23 ms) following STN DBS. TMS induced currents in 3 directions: lateral-medial (LM) direction activated corticospinal axons directly, posterior-anterior (PA), and anterior-posterior (AP) directions activated corticospinal neurons transynaptically. Motor-evoked potentials (MEP) elicited by AP and PA TMS were facilitated at short (2-4 ms) and medium latencies (21-24 ms). However, MEPs elicited by LM TMS were not modified by STN DBS. Short-latency antidromic stimulation of the corticosubthalamic projections and medium latency transmission likely through the basal ganglia-thalamocortical circuit led to cortical evoked potentials and increased motor cortex excitability at specific intervals following STN stimulation at clinically effective contacts. Cortical activation may be related to the clinical effects of STN DBS in PD.
authors.affiliation: Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada M5T 2S8.
authors.forename: Renju
authors.initials: R
authors.lastname: Kuriakose
authors.forename: Utpal
authors.initials: U
authors.lastname: Saha
authors.forename: Gabriel
authors.initials: G
authors.lastname: Castillo
authors.forename: Kaviraja
authors.initials: K
authors.lastname: Udupa
authors.forename: Zhen
authors.initials: Z
authors.lastname: Ni
authors.forename: Carolyn
authors.initials: C
authors.lastname: Gunraj
authors.forename: Filomena
authors.initials: F
authors.lastname: Mazzella
authors.forename: Clement
authors.initials: C
authors.lastname: Hamani
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
authors.forename: Elena
authors.initials: E
authors.lastname: Moro
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
authors.forename: Mojgan
authors.initials: M
authors.lastname: Hodaie
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000368:Aged; D046690:Deep Brain Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009476:Neurons, Efferent / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy*; D011712:Pyramidal Tracts / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D020531:Subthalamic Nucleus / Q000033:anatomy & histology / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D050781:Transcranial Magnetic Stimulation