The effects of transcranial direct current on memory and inhibitory control

 Transcranial direct current stimulation is a neuromodulator treatment that uses constant, weak currents directly to the scalp using electrodes on a cap. Some studies have been done on tDCS to see if it is an effective treatment for depression or its effectiveness at neuromodulation at all because the scalp and skull attenuate the majority of the current. The study "The peripheral effect of direct current stimulation on brain circuits involving memory" by Sven Vanneste et al., researchers the effects of tDCS has on memory and different pathways that can be modulated for this to occur. They hypothesize that activation of the greater occipital nerve using tDCS  (ON-tDCS) will upregulate memory performance due to the activation of the LC-NA pathway. This is coupled with their hypothesis that ON-tDCS activates the LC-NA pathway and enhances communication between the LC, amygdala, and hippocampus, which will create lasting effects on memory due to enhanced consolidation. Research from their study supports their hypothesis that ON-tDCS affects memory through the activation of the LC-NA pathway. It also shows that ON-tDCS modulates the medial temporal cortex with phase-amplitude coupling between theta and gamma oscillations, which further encodes memory representations. Another study researches the effects of tDCS, but focuses on its ability to treat ADHD. The article, "Transcranial direct current stimulation in attention-deficit hyperactivity disorder: A meta-analysis of neuropsychological deficits'' by Lias B. Razza et al., reviews and analyzes 10 studies that use tDCS to target inhibitory control and/or working memory in people with ADHD. The result of their analyses found that tDCS significantly improved inhibitory control in participants. Sub-analyses found that tDCS targeting the dorsolateral prefrontal cortex and anodal tDCS significantly improved inhibitory control, with anodal dorsolateral prefrontal cortex tDCS having the most significant effect on inhibitory control. They also found that tDCS had an improving effect on inhibiting control accuracy, but not response time, and working memory speed, but not accuracy. Overall, tDCS improved inhibitory control and working memory in people with ADHD with a small-to-medium effect size. Both articles provide evidence that tDCS can improve memory. With the evidence from these articles supporting tDCS as being effective at modulating memory and inhibitory control by targeting direct brain structures or peripheral pathways, can tDCS be an effective at treating other neuropsychiatric disorders that affect inhibitory control and working memory such as Obsessive Compulsive Disorder, Autism Spectrum Disorder, Tourette's, Schizophrenia, and memory disorders. If it is proven that tDCS is an effective treatment, should it be a more prominent treatment for these disorders if they are resistant to medication, in or even be used before medication treatment? Treatment using tDCS can be done in the home by the patient if trained, so it would make the treatment much more accessible and affordable for people.

 

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Lais B. Razza a b c, Razza, L. B., Luethi, M. S., Zanao, T., De Smet, S., Buchpiguel, C., Busatto, G., Pereira, J., Klein, I., Kappen, M., Moreno, M., Beaken, C., Vanderhasselt, M.-A., & Brunoni, A. R. (2022, September 12). Transcranial direct current stimulation versus intermittent theta-burst stimulation for the improvement of working memory performance. International Journal of Clinical and Health Psychology. Retrieved May 3, 2023, from https://www.sciencedirect.com/science/article/pii/S1697260022000424

 

Vanneste, S., Mohan, A., Yoo, H. B., Huang, Y., Luckey, A. M., McLeod, S. L., Tabet, M. N., Souza, R. R., McIntyre, C. K., Chapman, S., Robertson, I. H., & To, W. T. (2020). The peripheral effect of direct current stimulation on brain circuits involving memory. Science Advances, 6(45). https://doi.org/10.1126/sciadv.aax9538