If the thought you are thinking is actually a new thought, a new concept, a new technique that you've never thought of before, that's symbolized by this new pattern towards the bottom of the 'pinball machine' (metaphor) in your brain.
To get to this new place, you need a different way of thinking, a new perspective in a sense.
And that's provided by the diffuse mode.
When you think a thought, it takes off, and it can range very widely as you're attempting to come up with some new ideas.