title: Cortical neuromodulation modifies cerebral vasomotor reactivity.
abstract: OBJECTIVE
  Cerebral vasomotor reactivity (VMR) is a capability of cerebral vessels to dilate in response to hypercapnia. Transcranial direct current stimulation (tDCS) effects on cerebral hemodynamics have been poorly studied.
  
  
  METHODS
  Ten healthy subjects underwent anodal/cathodal tDCS on the left motor cortex. Before and after tDCS, VMR assessment by transcranial Doppler and an electrocardiogram were performed. Normalized low-frequency band power of heart rate variability and its reactivity from basal to VMR condition (LFN(react)) were estimated as relative markers of sympathetic activation. tDCS exerted a polarity-specific effect on both VMR (P=0.0001) and LFN(react) (P=0.001). Anodal tDCS decreased VMR by 3.4%/mm Hg CO(2) bilaterally and increased LFN(react), whereas cathodal tDCS increased VMR by 0.8%/mm Hg CO(2) bilaterally and reduced LFN(react).
  
  
  CONCLUSIONS
  Cerebral VMR is modified by tDCS. Based on the consensual changes with heart rate variability, we can hypothesize that the sympathetic nervous system could modulate the bihemispheric modification of VMR. Further studies are needed to confirm this hypothesis.
authors.affiliation: Neurologia Clinica, Università Campus Bio-Medico, Via Alvaro del Portillo 200, Roma 00128, Italy. f.vernieri@unicampus.it
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vernieri
authors.forename: Giovanni
authors.initials: G
authors.lastname: Assenza
authors.forename: Paola
authors.initials: P
authors.lastname: Maggio
authors.forename: Francesco
authors.initials: F
authors.lastname: Tibuzzi
authors.forename: Filippo
authors.initials: F
authors.lastname: Zappasodi
authors.forename: Claudia
authors.initials: C
authors.lastname: Altamura
authors.forename: Marzia
authors.initials: M
authors.lastname: Corbetto
authors.forename: Laura
authors.initials: L
authors.lastname: Trotta
authors.forename: Paola
authors.initials: P
authors.lastname: Palazzo
authors.forename: Matilde
authors.initials: M
authors.lastname: Ercolani
authors.forename: Franca
authors.initials: F
authors.lastname: Tecchio
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004558:Electric Stimulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*