Apparently this works on healthy people as well (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5592297/). "it was proposed that use of emerging brain stimulation techniques might also enhance physical and mental performance in sports." Anybody...want to try it?
"Stimulation to the the posterior parietal cortex facilitated numerical learning, whereas automaticity for the learned material was impaired." Fascinating.
https://www.jneurosci.org/content/33/10/4482.abstract