Highlights
- •We propose the first systematic paradigm for studying effects of tDCS on sentence production.
- •Anodal tDCS of PFC reliably decreased the rate of omitted and errorful sentences.
- •A reliable decrease was found for errors due to premature commitment.
- •A marginal effect was found for perseveratory errors.
Abstract
Background
Most studies in which Anodal Transcranial Direct Current Stimulation (A-tDCS) has
been used to improve language production have focused on single words. Yet sentence
production requires more than lexical retrieval. For example, successful suppression
of the past and careful planning of the future are two critical requirements for producing
a correct sentence. Can A-tDCS improves those, and by extension, production at the
sentence level?
Objective/Hypothesis
Given that many aspects of sentence production beyond word retrieval require frontally-mediated
operations, we hypothesized that A-tDCS to the left prefrontal cortex should benefit
various operation involved in producing sentences, two of which, suppression of the
past and planning of the future, were targeted in this study.
Methods
We used a paradigm that elicited construction of sentences through event description,
but was structured enough to allow for between-subject comparison, clear error identification,
and implementation of experimental manipulations to probe certain aspects of production.
Results
We showed that A-tDCS to the left PFC reliably decreased the number of incomplete
and errorful sentences. When the origin of this improvement was probed, we found that
A-tDCS significantly decreased errors due to premature commitment to the future word
(insufficient internal monitoring), and had a marginal effect on errors of perseverations
(insufficient suppression of the past).
Conclusion
We conclude that A-tDCS is a promising tool for improving production at the sentence
level, and that improvement can be expected when internal monitoring and control over
verbal responses is impaired, or for certain cases of perseveratory errors.
Keywords
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Article info
Publication history
Published online: July 23, 2014
Accepted:
July 14,
2014
Received in revised form:
July 14,
2014
Received:
April 3,
2014
Footnotes
Conflict of interest statement: None of the authors has a conflict of interest.
Identification
Copyright
© 2014 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
