title: Acute vagus nerve stimulation using different pulse widths produces varying brain effects.
abstract: BACKGROUND
  Vagus nerve stimulation (VNS) is an approved treatment for epilepsy and has been investigated in clinical trials of depression. Little is known about the relationship of VNS parameters to brain function. Using the interleaved VNS /functional magnetic resonance imaging (fMRI) technique, we tested whether variations of VNS pulse width (PW) would produce different immediate brain activation in a manner consistent with single neuron PW studies.
  
  
  METHODS
  Twelve adult patients with major depression, treated with VNS, underwent three consecutive VNS/fMRI scans, each randomly using one of three PWs (130 micros, 250 micros, or 500 micros). The data were analyzed with SPM2.
  
  
  RESULTS
  Global activations induced by PWs 250 and 500 were both significantly greater than that induced by PW 130 but not significantly different from each other. For global deactivation, PWs 130 and 250 were both significantly greater than PW 500 but not significantly different from each other. Regional similarities and differences were also seen with the various PWs.
  
  
  CONCLUSIONS
  The data confirm our hypothesis that VNS at PW 500 globally produces no more activation than does PW 250, and PW 130 is insufficient for activation of some regions. These data suggest that PW is an important variable in producing VNS brain effects.
authors.affiliation: Brain Stimulation Laboratory, Medical University of South Carolina, Institute of Psychiatry 502N, 67 President Street, Charleston, SC 29425, USA.
authors.forename: Qiwen
authors.initials: Q
authors.lastname: Mu
authors.forename: Daryl E
authors.initials: DE
authors.lastname: Bohning
authors.forename: Ziad
authors.initials: Z
authors.lastname: Nahas
authors.forename: John
authors.initials: J
authors.lastname: Walker
authors.forename: Berry
authors.initials: B
authors.lastname: Anderson
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Johnson
authors.forename: Stewart
authors.initials: S
authors.lastname: Denslow
authors.forename: Mikhail
authors.initials: M
authors.lastname: Lomarev
authors.forename: Poya
authors.initials: P
authors.lastname: Moghadam
authors.forename: Jeong-Ho
authors.initials: JH
authors.lastname: Chae
authors.forename: Mark S
authors.initials: MS
authors.lastname: George
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D003865:Major Depressive Disorder / Q000628:therapy*; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012039:Regional Blood Flow; D016037:Single-Blind Method; D013997:Time Factors; D014630:Vagus Nerve / Q000528:radiation effects*
chemical_list: D010100:Oxygen