title: Cerebral activation during vagus nerve stimulation: a functional MR study.
abstract: OBJECTIVE
  To study the short-term effects of vagus nerve stimulation (VNS) on brain activation and cerebral blood flow by using functional magnetic resonance imaging (fMRI).
  
  
  METHODS
  Five patients (three women, two men; mean age, 35.4 years) who were treated for medically refractory epilepsy with VNS, underwent fMRI. All patients had a nonfocal brain MRI. The VNS was set at 30 Hz, 0.5-2.0 mA for intervals of activation of 30 s on and 30 s off, during which the fMRI was performed. Statistical parametric mapping (SPM) was used to determine significant areas of activation or inhibition during vagal nerve stimulation (p < 0.05).
  
  
  RESULTS
  VNS-induced activation was detected in the thalami bilaterally (left more than right), insular cortices bilaterally, ipsilateral basal ganglia and postcentral gyri, right posterior superior temporal gyrus, and inferomedial occipital gyri (left more than right). The most robust activation was seen in the thalami (left more than right) and insular cortices.
  
  
  CONCLUSIONS
  VNS-induced thalamic and insular cortical activation during fMRI suggests that these areas may play a role in modulating cerebral cortical activity, and the observed decrease in seizure frequency in patients who are given VNS may be a consequence of this increased activation.
authors.affiliation: Department of Neurology, New York Presbyterian Hospital-Weill Cornell Medical Center, New York, New York 10021, USA.
authors.forename: Jaishree T
authors.initials: JT
authors.lastname: Narayanan
authors.forename: Richard
authors.initials: R
authors.lastname: Watts
authors.forename: Naim
authors.initials: N
authors.lastname: Haddad
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Labar
authors.forename: P Mark
authors.initials: PM
authors.lastname: Li
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Filippi
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D004599:Electric Stimulation Therapy; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology / Q000628:therapy*; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000503:physiopathology; D013788:Thalamus / Q000503:physiopathology; D014630:Vagus Nerve / Q000503:physiopathology*