Vagus Nerve Stimulation Applied with a Rapid Cycle Has More Profound Influence on Hippocampal Electrophysiology Than a Standard Cycle.
Although vagus nerve stimulation (VNS) is widely used, therapeutic mechanisms and optimal stimulation parameters remain elusive. In the present study, we investigated the effect of VNS on hippocampal field activity and compared the efficiency of different VNS paradigms. Hippocampal electroencephalography (EEG) and perforant path dentate field-evoked potentials were acquired before and during VNS in freely moving rats, using 2 VNS duty cycles: a rapid cycle (7 s on, 18 s off) and standard cycle (30 s on, 300 s off) and various output currents. VNS modulated the evoked potentials, reduced total power of the hippocampal EEG, and slowed the theta rhythm. In the hippocampal EEG, theta (4-8 Hz) and high gamma (75-150 Hz) activity displayed strong phase amplitude coupling that was reduced by VNS. Rapid-cycle VNS had a greater effect than standard-cycle VNS on all outcome measures. Using rapid cycle VNS, a maximal effect on EEG parameters was found at 300 μA, beyond which effects saturated. The findings suggest that rapid-cycle VNS produces a more robust outcome than standard cycle VNS and support already existing preclinical evidence that relatively low output currents are sufficient to produce changes in brain physiology and thus likely also therapeutic efficacy.
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium. larsemil.larsen@ugent.be.
Lars E
LE
Larsen
Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
Wytse J
WJ
Wadman
Department of Data Analysis, Faculty for Psychological and Pedagogical Sciences, Ghent University, Ghent, Belgium.
Daniele
D
Marinazzo
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.|Medical Imaging and Signal Processing, Department of Electronics and Information Systems, iMinds Medical IT Department, Ghent University, Ghent, Belgium.
Pieter
P
van Mierlo
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Jean
J
Delbeke
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Sofie
S
Daelemans
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Mathieu
M
Sprengers
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Lisa
L
Thyrion
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Wouter
W
Van Lysebettens
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Evelien
E
Carrette
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Paul
P
Boon
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Kristl
K
Vonck
Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology (LCEN3), Ghent University, Ghent, Belgium.
Robrecht
R
Raedt
D000818:Animals; D058256:Brain Waves; D018891:Dentate Gyrus / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials; D019706:Excitatory Postsynaptic Potentials; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D019580:Perforant Pathway / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted; D055536:Vagus Nerve Stimulation / Q000379:methods*
Dentate gyrus; EEG; Evoked potential; Phase amplitude coupling; Stimulation parameters; Vagus nerve stimulation