the thorax oscillates very rapidly to help coordinate the fast frequency of wings during flight. this oscillation is usually faster than what the brain typically controls (also thinking about central pattern generators here). All the brain needs to do is make sure that power muscles are activated in order to drive thoracic oscillations. This can probably occur through bursting activity of neurons.
There is one caveat to this adaptation though. coupling wings to the thorax is helpful for general flight but constrains wings from moving independently, which is needed for steering.