nugpot,
the A/T system is not a separate system on the B777 as on other 'fly-by-wire' aircrafts. when the A/Ts are engaged, the A/T servos moves the throttle levers just as a pilot will normally do, based on the A/T computer inputs. one can manually 'overwrite' the servos by physically moving the throttle levers but if you released the throttles, the A/T servos will move the throttle levers back to it's 'current commanded' position.
SR