Electroencephalography-guided transcranial direct current stimulation improves picture-naming performance.

Area of Science:

• Neuroscience
• Cognitive Science
• Neuromodulation

Background:

• Transcranial direct current stimulation (tDCS) is explored for enhancing verbal function by targeting Broca's area.
• Functional magnetic resonance imaging (fMRI) has been used to optimize tDCS targeting, but the efficacy of electroencephalography (EEG) for this purpose is less understood.

Purpose of the Study:

• To investigate if EEG can identify optimal stimulation sites for tDCS to improve verbalization during a picture-naming task.
• To compare the effectiveness of EEG-guided tDCS with direct stimulation of Broca's area and sham stimulation.

Main Methods:

• Experiment 1: Acquired simultaneous EEG and fMRI data during a naming task in 21 participants to compare activation areas.
• Experiment 2: Administered tDCS in a crossover design to 15 participants, targeting EEG-identified areas, Broca's area, and a sham condition.
• Utilized a picture-naming task to assess verbalization performance.

Main Results:

• EEG and fMRI data showed overlapping areas of maximal activation in 80% of participants.
• tDCS applied to the EEG-guided area significantly improved lexical retrieval speed compared to stimulation over Broca's area.
• EEG-guided tDCS demonstrated superior performance compared to the sham condition.

Conclusions:

• EEG is a valid method for identifying optimal brain areas for tDCS targeting.
• EEG-guided tDCS effectively enhances language function, specifically lexical retrieval speed.
• This approach offers a practical method for optimizing tDCS efficacy in clinical and research settings.