Boffins upload worm's brain into a computer, teach it tricks

I'm confused. Where does the pole (on the tail) come from? Now I follow that they programmed the brain of the worm and, I presume, they also thus programmed something to mimic the 'body' (?) motion (to show output from the 'brain?)', but what about this pole?

Did someone leave a 'pole' subroutine lying somewhere in a library and the 'body' coder just accidentally tacked it on the end? Did they then magically notice the pole-code doing something? Or did someone randomly think "I know, I'll stick a pole on it's arse" - and if so, why a pole and not a beeper, or a LED, or a wifi link to a nuclear trigger?! How did they think "this will end up with it balancing a pole" if they didn't know the learning outcome?

(Even reading about this stuff is obviously waaaaay beyond me! Especially on a Monday. And a Friday. And all other days).

SB