Abstract
Background.
A successful interplay between prefrontal and domain-specific language
areas is critical for language processing. Previous studies involving
people with aphasia have shown that executive control processes might
act on lexical-semantic representations during retrieval. Modulating the
prefrontal control network by means of noninvasive brain stimulation
might, therefore, improve lexical access in people with aphasia.
Objective.
The present study investigates the effects of prefrontal transcranial
direct current stimulation (tDCS) on lexical access in chronic
poststroke aphasia.
Methods. We report data of 14 participants
with chronic poststroke aphasia. We used a sham-tDCS (S-tDCS) controlled
and double-blind within-subjects design. Performances in picture
naming, verbal fluency, and word repetition were assessed immediately
after stimulation.
Results. As compared with S-tDCS, anodal tDCS
(A-tDCS) improved verbal fluency as well as the speed of naming high
frequency words, but not word repetition.
Conclusion. The results
of our study suggest that the brain network dedicated to lexical
retrieval processing can be facilitated by A-tDCS over the left
dorsolateral prefrontal cortex. This finding supports the notion that
strengthening executive control functions after stroke could complement
speech and language-focused therapy.
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