That is your stimuli is converted into electro magnetic wave and is sent across and this is received by the Brain and it decodes and assigns the messages to their respective slots in the Brain.
Now any and everything in the Universe vibrates from the Atom to the Galaxies.
So when the is a stimuli there is electro magnetic activity.
Ultimately our brain decodes everything electro magnetically and it is converted into understandable message when they are processed and sent back.
These vibrations as understood in the light of electromagnetism has thrown some interesting results.