Have Shimano 105 STI shifters on my road/cyclocross bike.
My mountain bike has some older type shifters, circa early 1990's. The components are mostly Shimano Acera LX. They are under the bar, have indexing that that shows which gear I'm in. I push forward and each click goes down a gear. I pull on the lever and each click brings it up a gear. Sorry... don't know the actual name of these type of shifters.
PBW