Involvement of Broca’s Area and Its Right Hemispheric Homologue in Acquiring Abstract and Concrete Semantics: Transcranial Direct Current Stimulation Study

— The study compared effects of transcranial direct current stimulation (tDCS) of Broca’s area and of its right hemispheric homologue on the acquisition of novel concrete and abstract words. Word/concept acquisition was achieved through reading sets of sentences, which incorporated novel words, gradually revealing their meaning through context. Before the learning session, a 15-min anodal or cathodal stimulation of one of the target areas was applied. A lexical decision task was used to assess the learning outcomes immediately after the learning session and 24 h later. The results showed a larger number of correct responses after right hemispheric tDCS, in comparison with that of Broca’s area in the left hemisphere. These results suggest that the right hemispheric counterpart of Broca’s area is involved in the processing and acquisition of new concrete and abstract semantics. Furthermore, they demonstrate facilitating effects of tDCS on the processes of overnight consolidation of newly formed word memory traces.