have there been any "scientific" tests on stuttering?

have there been any "scientific" tests on stuttering? I'm really curious as to whether there have been any or many studies related to stuttering and what was carried out during the test(s). I think it'd be interesting to measure the patients brain waves using EEG for a set period of time and around normal life and in set events. Of course there are many variables and everyone's stutter is different but it'd be nice to see I think