Transcranial Direct Current Stimulation in Voice and Speech Control: Scoping Review

Area of Science:

• Neuroscience
• Speech and Hearing Sciences
• Rehabilitation Medicine

Background:

• Voice and speech disorders affect millions globally.
• Non-invasive brain stimulation techniques offer novel therapeutic avenues.
• Transcranial direct current stimulation (tDCS) is emerging as a tool for modulating neural activity.

Purpose of the Study:

• To map brain areas stimulated by tDCS for voice and speech modulation.
• To summarize evidence on tDCS effects on vocal quality and parameters.
• To correlate tDCS outcomes with stimulated brain regions.

Main Methods:

• Systematic literature review of PubMed, Web of Science, and VHL databases.
• Search terms included "Transcranial direct current stimulation" AND "Voice quality OR singing OR speech OR voice".
• PCC framework used: Population (individuals undergoing tDCS for voice/speech), Concept (brain areas, stimulation type), Context (effects on voice/speech).

Main Results:

• Eight studies were included from an initial 919.
• Dorsolateral prefrontal cortex and left ventral motor cortex showed effects on vocal production and motor control.
• tDCS over the inferior parietal lobe modulated speech motor learning and vocal adaptation.

Conclusions:

• Anodal tDCS demonstrated improved motor adaptation to sensory alterations.
• tDCS shows potential as a therapeutic intervention for voice and speech enhancement.
• Further research is warranted to optimize tDCS protocols for clinical application.