The Brain Learns in Unexpected Ways is the headline of a long, and not-very-accessible, article in Scientific American.
However, if you dig through it, there are several passages that could be useful when teaching students about what happens to the brain when you learn something new. You can see the lesson I use at The Best Resources For Showing Students That They Make Their Brain Stronger By Learning.
Apart from the quote at the top of this post, the most helpful passages relate to how learning affect myelin, part of the brain’s white matter. You can read more about myelin at New Study: Sleep Boosts Production Of Myelin.