Bursts of electrical stimulation to a nerve in the face seem to improve signalling between neurons and people's performance on a memory test https://www.newscientist.com/article/2588180-zapping-the-face-could-boost-brain-signalling-and-memory/?utm_term=Autofeed&utm_campaign=echobox&utm_medium=social&utm_source=Twitter#Echobox=1789097841