check out this preprint - [orpella et al.](https://www.biorxiv.org/content/10.1101/2022.08.02.501857v1.full) .... shows greater activity in a cortical area (right preSMA) leading up to stuttering events. IMHO the best study so far investigating the moment-by-moment brain activity associated with stutering, and in a reasonably-sized group (n=29 stuttering adults)