tDCS of right-hemispheric Wernicke's area homologue affects contextual learning of novel lexicon

Neurobiol Learn Mem. 2024 Feb 23:107905. doi: 10.1016/j.nlm.2024.107905. Online ahead of print.ABSTRACTNumerous studies have shown robust evidence of the right hemisphere's involvement in language comprehension, for instance in the processing of intonation, grammar, prelexical processing stages, novel metaphor comprehension, etc. However, its role in lexicon acquisition remains obscure. We applied transcranial direct current stimulation (tDCS) over the right-hemispheric homologue of Wernicke's area to assess its putative involvement in processing different types of novel semantics. After receiving 15 min of anodal, cathodal, or sham (placebo) tDCS, three groups of healthy participants learnt novel concrete and abstract words in the context of short stories. Learning outcomes were assessed using a battery of tests immediately after this contextual learning session and 24 h later. As a result, an inhibitory effect of cathodal and facilitatory effect of anodal tDCS were found for abstract word acquisition only. We also found a significant drop in task performance on the second day of the assessment for both word types in all the stimulation groups, with no significant influence of tDCS on the post-learning consolidation of new memory traces. The results suggest an involvement of Wernicke's right-hemispheric counterpart in initial encoding (but not consolidation) of abstract semantics, which may be explained either by the right hemisphere's direct role in lexical semantic process...
Source: Neurobiology of Learning and Memory - Category: Neurology Authors: Source Type: research