It was talking about the flow of thoughts and how different neural circuits are activated when people engage in writing things down.
There is an old book called “Writing and thinking” which covers some of the ideas about how thought can be refined through language usage. Developing the language centers to work through writing is yet another way to have a more embodied sense of cognition and thinking. I recall reading somewhere that someone was able to get more “in the flow” using a fountain pen and cursive rather than more typical writing tools—mostly because the fountain pen itself changed the pacing of how his thoughts were expressed on paper… there are a lot of neat things that can be explored like that.
Even typing with a typewriter instead of on a computer (with spell checker and the internet) is a distinctly different experience.