title: The involvement of the left motor cortex in learning of a novel action word lexicon.
abstract: Current theoretical positions assume that action-related word meanings are established by functional connections between perisylvian language areas and the motor cortex (MC) according to Hebb's associative learning principle. To test this assumption, we probed the functional relevance of the left MC for learning of a novel action word vocabulary by disturbing neural plasticity in the MC with transcranial direct current stimulation (tDCS). In combination with tDCS, subjects learned a novel vocabulary of 76 concrete, body-related actions by means of an associative learning paradigm. Compared with a control condition with "sham" stimulation, cathodal tDCS reduced success rates in vocabulary acquisition, as shown by tests of novel action word translation into the native language. The analysis of learning behavior revealed a specific effect of cathodal tDCS on the ability to associatively couple actions with novel words. In contrast, we did not find these effects in control experiments, when tDCS was applied to the prefrontal cortex or when subjects learned object-related words. The present study lends direct evidence to the proposition that the left MC is causally involved in the acquisition of novel action-related words.
authors.affiliation: University Hospital Hamburg-Eppendorf, Department of Neurology, 20246 Hamburg, Germany.
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Liuzzi
authors.forename: Nils
authors.initials: N
authors.lastname: Freundlieb
authors.forename: Volker
authors.initials: V
authors.lastname: Ridder
authors.forename: Julia
authors.initials: J
authors.lastname: Hoppe
authors.forename: Kirstin
authors.initials: K
authors.lastname: Heise
authors.forename: Maximo
authors.initials: M
authors.lastname: Zimerman
authors.forename: Christian
authors.initials: C
authors.lastname: Dobel
authors.forename: Stefanie
authors.initials: S
authors.lastname: Enriquez-Geppert
authors.forename: Christian
authors.initials: C
authors.lastname: Gerloff
authors.forename: Pienie
authors.initials: P
authors.lastname: Zwitserlood
authors.forename: Friedhelm C
authors.initials: FC
authors.lastname: Hummel
mesh_terms: D000328:Adult; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009483:Neuropsychological Tests; D014706:Verbal Learning / Q000502:physiology*; D014825:Vocabulary; D055815:Young Adult