lomapaseo -
Most likely, they are track-ball housings. Rather than a mouse, you have a ball by which you move the cursor around the screen. If you've ever seen video of the inside of a P3 or E3, then that's what the crew are using to flick the cursor around their screens. In those aircraft they're mounted in a horizontal desk but here, they'd be below - hence mounting them proud would probably be the same ergonomically.