No Enhancing Effect of Fronto-Medial tDCS on Working Memory Processes
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It has been argued that transcranial direct current stimulation (tDCS) over the frontal cortex impacts, directly and indirectly, on oscillatory brain activity in the theta frequency range, and thus affects working memory. This study aims to clarify whether a tDCS montage with one electrode over a fronto-medial stimulation site and the return electrode on the chin can indeed modulate working memory performance. It was predicted that tDCS with the anode over the fronto-medial site should lead to better working memory performance compared to when the cathode is placed over the fronto-medial site. Eighty-four participants were divided into three groups receiving either 10-min sham, anodal, or cathodal stimulation at 2 mA offline between two blocks of a two-back task. No significant differences between stimulation conditions were found. Bayes statistics indicated moderate evidence that the null hypothesis is in fact true. This paper demonstrates that the fronto-medial tDCS montage has no functional impact on working memory performance. Future studies could investigate fronto-medial frequency-specific oscillatory electric stimulation in the theta frequency range. Such oscillatory electrical stimulation might be more successful than tDCS in modulating working memory processes.
KeywordsTranscranial direct current stimulation (tDCS) Frontal-midline theta Medial prefrontal cortex Negative findings
We would like to thank Stella Berboth, Axel Smith, and the LMU psychology undergraduate students for help with the data collection.
This research was funded by the German research council DFG SA1782/2-1.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
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