How do STI levers work?
May I be first with the standard Campag owners retort: "Not very well".
Having set that particualr bush fire ablaze, I'll try and bit a little more helpful.
Yes the gears and brakes are in a combined unit. In the UK on the right you have front bake, rear changer and on the left, rear brake and front changer.
You 'swing' the whole unit in to move the corresponding changer towards a bigger chain wheel, while the inner lever is again pushed inwards to drop the changer down one size.
So on the front STI the main movement is changing into a bigger gear, whereas the same movement on the rear STI is selecting a smaller gear.