title: Transcranial direct current stimulation enhances sucking of a liquid bolus in healthy humans.
abstract: BACKGROUND
  Transcranial direct current stimulation (tDCS) is a non-invasive technique used for modulating cortical excitability in vivo in humans. Here we evaluated the effect of tDCS on behavioral and electrophysiological aspects of physiological sucking and swallowing.
  
  
  METHODS
  Twelve healthy subjects underwent three tDCS sessions (anodal, cathodal and sham stimulation) on separate days in a double-blind randomized order. The active electrode was placed over the right swallowing motor cortex. Repeated sucking and swallowing acts were performed at baseline and at 15 and 60 min after each tDCS session and the mean liquid bolus volume ingested at each time point was measured. We also calculated average values of the following electrophysiological parameters: 1) area and 2) duration of the rectified EMG signal from the suprahyoid/submental muscles related to the sucking and swallowing phases; 3) EMG peak amplitude for the sucking and swallowing phases; 4) area and peak amplitude of the laryngeal-pharyngeal mechanogram; 5) oropharyngeal delay.
  
  
  RESULTS
  The volume of the ingested bolus significantly increased (by an average of about 30% compared with the baseline value) both at 15 and at 60 min after the end of anodal tDCS. The electrophysiological evaluation after anodal tDCS showed a significant increase in area and duration of the sucking phase-related EMG signal.
  
  
  CONCLUSIONS
  Anodal tDCS leads to stronger sucking of a liquid bolus in healthy subjects, likely by increasing recruitment of cortical areas of the swallowing network. This finding might open up interesting perspectives for the treatment of patients suffering from dysphagia due to various pathological conditions.
authors.affiliation: Department of Experimental Biomedicine and Clinical Neurosciences (BioNeC), University of Palermo, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cosentino
authors.affiliation: Department of Neurophysiopathology, C. Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy. Electronic address: enrico.alfonsi@mondino.it.
authors.forename: Enrico
authors.initials: E
authors.lastname: Alfonsi
authors.affiliation: Department of Experimental Biomedicine and Clinical Neurosciences (BioNeC), University of Palermo, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Brighina
authors.affiliation: Department of Neurophysiopathology, C. Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Fresia
authors.affiliation: Department of Experimental Biomedicine and Clinical Neurosciences (BioNeC), University of Palermo, Italy.
authors.forename: Brigida
authors.initials: B
authors.lastname: Fierro
authors.affiliation: Department of Neurophysiopathology, C. Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy; Department of Brain and Behaviour, University of Pavia, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Sandrini
authors.affiliation: Department of Clinical Sciences "L. Sacco", University of Milan, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Schindler
authors.affiliation: Department of Experimental Biomedicine and Clinical Neurosciences (BioNeC), University of Palermo, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Valentino
authors.affiliation: Department of Neurophysiopathology, C. Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Fontana
authors.affiliation: Department of Neurological Sciences, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Priori
mesh_terms: D000328:Adult; D000368:Aged; D003679:Deglutition / Q000502:physiology; D003680:Deglutition Disorders; D004311:Double-Blind Method; D004576:Electromyography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007830:Larynx / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010614:Pharynx / Q000502:physiology; D013391:Sucking Behavior / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Brain stimulation; Dysphagia; Electromyography; Suction; Swallowing; tDCS