New research further clarifies how different areas of the brain process different parts of the creation and expression of a thought. Here's the summary article: https://www.sciencedaily.com/releases/2022/01/220112093712.htm, and the Nature Communications research paper here: https://www.nature.com/articles/s41467-021-27725-3.
I found this bit of discovery especially interesting: "First of all, the oscillations called theta (4-8Hz), which correspond to the average rhythm of syllable elocution. Then the gamma frequencies (25-35Hz), observed in the areas of the brain where speech sounds are formed. Thirdly, beta waves (12-18Hz) related to the cognitively more efficient regions solicited, for example to anticipate and predict the evolution of a conversation. Finally, the high frequencies (80-150Hz) that are observed when a person speaks out"