title: Modulation of Gestural-verbal Semantic Integration by tDCS.
abstract: BACKGROUND
  Understanding actions based on either language or observation of gestures is presumed to involve the motor system, and reflect the engagement of an embodied conceptual network. The role of the left inferior frontal gyrus (IFG) in language tasks is well established, but the role of the right hemisphere is unclear with some imaging evidence suggesting right IFG activation when gestures mismatch speech.
  
  
  OBJECTIVE
  Using transcranial direct current stimulation (tDCS), we explored the hemispheric asymmetries in the assumed cognitive embodiment required for gestural-verbal integration.
  
  
  METHODS
  Symbolic gestures served as primes for verbal targets. Primes were clips of symbolic gestures taken from a rich set of emblems and pantomimes. Participants responded by performing a semantic relatedness-judgment under 3 stimulation conditions - anodal tDCS (atDCS) over the left IFG, atDCS over the right IFG, and sham. There was also a non-semantic control task of attentional load.
  
  
  RESULTS
  AtDCS of the right IFG generated faster responses to symbolic gestures than atDCS over the left IFG or sham stimulation. For the attentional load task, no differences were observed across the three stimulation conditions. These results support a right-lateralization bias of the human mirror neuron system in processing gestural-verbal stimuli.
  
  
  CONCLUSIONS
  Gesture comprehension may be enhanced by improved gesture and language integration.
authors.affiliation: Department of Psychology, Bar Ilan University, Ramat Gan, Israel.
authors.forename: Tania
authors.initials: T
authors.lastname: Cohen-Maximov
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Keren
authors.initials: K
authors.lastname: Avirame
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Flöel
authors.affiliation: Department of Psychology, Bar Ilan University, Ramat Gan, Israel; The Gonda Brain Research Center, Bar Ilan University, Israel. Electronic address: michal.lavidor@gmail.com.
authors.forename: Michal
authors.initials: M
authors.lastname: Lavidor
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D005868:Gestures; D006801:Humans; D008297:Male; D008875:Middle Aged; D059167:Mirror Neurons / Q000502:physiology; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D065908:Transcranial Direct Current Stimulation; D014705:Verbal Behavior / Q000502:physiology*; D055815:Young Adult
keywords: Lateralization; Mirror neuron system; Semantic priming; Symbolic gestures; tDCS