Dorsolateral Prefrontal Transcranial Direct Current Stimulation Modulates Language Processing but Does Not Facilitate Overt Second Language Word Production

Radman, Narges; Britz, Juliane; Bütler, Karin; Weekes, Brendan S.; Spierer, Lucas; Annoni, Jean-Marie (2018). Dorsolateral Prefrontal Transcranial Direct Current Stimulation Modulates Language Processing but Does Not Facilitate Overt Second Language Word Production. Frontiers in neuroscience, 12(490), p. 490. Frontiers Research Foundation 10.3389/fnins.2018.00490

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Word retrieval in bilingual speakers partly depends on executive control systems in the left prefrontal cortex - including dorsolateral prefrontal cortex (DLPFC). We tested the hypothesis that DLPFC modulates word production of words specifically in a second language (L2) by measuring the effects of anodal transcranial direct current stimulation (anodal-tDCS) over the DLPFC on picture naming and word translation and on event-related potentials (ERPs) and their sources. Twenty-six bilingual participants with "unbalanced" proficiency in two languages were given 20 min of 1.5 mA anodal or sham tDCS (double-blind stimulation design, counterbalanced stimulation order, 1-week intersession delay). The participants then performed the following tasks: verbal and non-verbal fluency during anodal-tDCS stimulation and first and second language (L1 and L2) picture naming and translation [forward (L1 → L2) and backward (L2 → L1)] immediately after stimulation. The electroencephalogram (EEG) was recorded during picture naming and translation. On the behavioral level, anodal-tDCS had an influence on non-verbal fluency but neither on verbal fluency, nor on picture naming and translation. EEG measures revealed significant interactions between Language and Stimulation on picture naming around 380 ms post-stimulus onset and Translation direction and Stimulation on translation around 530 ms post-stimulus onset. These effects suggest that L2 phonological retrieval and phoneme encoding are spatially and temporally segregated in the brain. We conclude that anodal-tDCS stimulation has an effect at a neural level on phonological processes and, critically, that DLPFC-mediated activation is a constraint on language production specifically in L2.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > ARTORG Center for Biomedical Engineering Research > ARTORG Center - Motor Learning and Neurorehabilitation
10 Strategic Research Centers > ARTORG Center for Biomedical Engineering Research > ARTORG Center - Gerontechnology and Rehabilitation

UniBE Contributor:

Bütler, Karin

Subjects:

400 Language > 410 Linguistics
600 Technology > 610 Medicine & health

ISSN:

1662-4548

Publisher:

Frontiers Research Foundation

Language:

English

Submitter:

Angela Amira Botros

Date Deposited:

08 Apr 2019 14:25

Last Modified:

23 Oct 2019 07:23

Publisher DOI:

10.3389/fnins.2018.00490

PubMed ID:

30090054

BORIS DOI:

10.7892/boris.124906

URI:

https://boris.unibe.ch/id/eprint/124906

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