TY - JOUR

T1 - Acquisition of concrete and abstract words is modulated by tDCS of Wernicke’s area

AU - Kurmakaeva, Diana

AU - Blagovechtchenski, Evgeny

AU - Gnedykh, Daria

AU - Mkrtychian, Nadezhda

AU - Kostromina, Svetlana

AU - Shtyrov, Yury

N1 - Funding Information: Supported by RF Government grant contract No.14.W03.31.0010. We would like to thank Drs Margarita Filip-pova and Olga Shcherbakova for their assistance in creating the stimulus set, Dr Andriy Myachykov for his guidance in implementing F2 ANOVA and Dr Ekaterina Perikova for her help in participant recruitment. We are also most grateful to the two reviewers of the earlier versions of this paper for their insightful comments and helpful suggestions. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/1/15

Y1 - 2021/1/15

N2 - Previous behavioural and neuroimaging research suggested distinct cortical systems involved in processing abstract and concrete semantics; however, there is a dearth of causal evidence to support this. To address this, we applied anodal, cathodal, or sham (placebo) tDCS over Wernicke’s area before a session of contextual learning of novel concrete and abstract words (n = 10 each), presented five times in short stories. Learning effects were assessed at lexical and semantic levels immediately after the training and, to attest any consolidation effects of overnight sleep, on the next day. We observed successful learning of all items immediately after the session, with decreased performance in Day 2 assessment. Importantly, the results differed between stimulation conditions and tasks. Whereas the accuracy of semantic judgement for abstract words was significantly lower in the sham and anodal groups on Day 2 vs. Day 1, no significant performance drop was observed in the cathodal group. Similarly, the cathodal group showed no significant overnight performance reduction in the free recall task for either of the stimuli, unlike the other two groups. Furthermore, between-group analysis showed an overall better performance of both tDCS groups over the sham group, particularly expressed for abstract semantics and cathodal stimulation. In sum, the results suggest overlapping but diverging brain mechanisms for concrete and abstract semantics and indicate a larger degree of involvement of core language areas in storing abstract knowledge. Furthermore, they demonstrate a possiblity to improve learning outcomes using neuromodulatory techniques.

AB - Previous behavioural and neuroimaging research suggested distinct cortical systems involved in processing abstract and concrete semantics; however, there is a dearth of causal evidence to support this. To address this, we applied anodal, cathodal, or sham (placebo) tDCS over Wernicke’s area before a session of contextual learning of novel concrete and abstract words (n = 10 each), presented five times in short stories. Learning effects were assessed at lexical and semantic levels immediately after the training and, to attest any consolidation effects of overnight sleep, on the next day. We observed successful learning of all items immediately after the session, with decreased performance in Day 2 assessment. Importantly, the results differed between stimulation conditions and tasks. Whereas the accuracy of semantic judgement for abstract words was significantly lower in the sham and anodal groups on Day 2 vs. Day 1, no significant performance drop was observed in the cathodal group. Similarly, the cathodal group showed no significant overnight performance reduction in the free recall task for either of the stimuli, unlike the other two groups. Furthermore, between-group analysis showed an overall better performance of both tDCS groups over the sham group, particularly expressed for abstract semantics and cathodal stimulation. In sum, the results suggest overlapping but diverging brain mechanisms for concrete and abstract semantics and indicate a larger degree of involvement of core language areas in storing abstract knowledge. Furthermore, they demonstrate a possiblity to improve learning outcomes using neuromodulatory techniques.

KW - DIRECT-CURRENT STIMULATION

KW - NONINVASIVE BRAIN-STIMULATION

KW - CONTEXT-AVAILABILITY

KW - SEMANTIC SYSTEM

KW - MOTOR CORTEX

KW - HEALTHY

KW - COMPREHENSION

KW - EXCITABILITY

KW - FMRI

KW - CONSOLIDATION

UR - http://www.scopus.com/inward/record.url?scp=85100200111&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/5a40c7d9-2618-3eff-b6ed-d497149838d1/

U2 - 10.1038/s41598-020-79967-8

DO - 10.1038/s41598-020-79967-8

M3 - Article

C2 - 33452288

AN - SCOPUS:85100200111

VL - 11

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 1508

ER -