Augmentation of working memory training by transcranial direct current stimulation (tDCS)

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuromodulation

Background:

• Transcranial direct current stimulation (tDCS) modulates dorsolateral prefrontal cortex (dlPFC) activity, impacting working memory (WM).
• Existing research on tDCS-enhanced WM training shows ambiguous results regarding sustainability and transferability.
• WM performance exhibits lateralization based on stimulus type, suggesting a potential for targeted tDCS application.

Purpose of the Study:

• To investigate the efficacy of task-congruent versus task-incongruent tDCS applied to the dlPFC for enhancing WM training.
• To assess the sustainability and transferability of WM training gains achieved with tDCS.
• To explore the neuroplastic effects of tDCS in relation to WM training.

Main Methods:

• A randomized, sham-controlled experiment involving 71 healthy adults trained on spatial or verbal adaptive n-back tasks.
• Anodal or sham tDCS (1 mA) applied to the left or right dlPFC during three WM training sessions.
• Evaluation of training gains, sustainability (up to nine months), and near-transfer to untrained tasks.

Main Results:

• WM training combined with task-congruent tDCS resulted in a steeper learning curve compared to sham stimulation.
• This enhancement was also significantly greater than with task-incongruent tDCS.
• Training-induced improvements were sustained for up to nine months and transferred to untrained tasks.

Conclusions:

• Task-congruent tDCS facilitates a behaviorally relevant and sustainable enhancement of WM training.
• These findings demonstrate tDCS's potential to modulate neuroplasticity for treating WM deficits.
• The study highlights the importance of stimulus-specific tDCS application for optimizing cognitive training outcomes.