The nature and time course of cortical activation following subthalamic stimulation in Parkinson's disease.
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.
Kuriakose
Renju
R
Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada M5T 2S8.
Saha
Utpal
U
Castillo
Gabriel
G
Udupa
Kaviraja
K
Ni
Zhen
Z
Gunraj
Carolyn
C
Mazzella
Filomena
F
Hamani
Clement
C
Lang
Anthony E
AE
Moro
Elena
E
Lozano
Andres M
AM
Hodaie
Mojgan
M
Chen
Robert
R
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