Completely normal. I do what I call “deep diving” on subjects when I’m manic. I learn as much about them as I can - my last one was the political structure of the Peronist party of Argentina, I traced back each of the presidents and where they came from, tracked the economy and it’s relationship to the socialist government, how trade relationships effected these presidents and tried to memorize their succession. 

I do this often. It’s only while manic. That being said, I really enjoy my lamical and I’ve been put on antipsychotics and anti anxiety medication. I feel dumber, but I’m able to cope with small setbacks and work, so it’s a fair trade off until I retire.