I consider this boundary to be essentially meaningless myself, btw, since I
find it almost impossible to think without some kind of “motor” movement
taking place, even if it’s just my eyes flitting around, but more often, my hands
and voice as well, even if it’s under my breath.
Or as Rodolfo Llinás puts it:
″… thinking may be nothing else but internalized movement.”
“So thinking is a premotor act.”