This is a recently released article so I'm having a difficult time finding/pirating a full version, but I"ll relate what I understand from the abstract. ​ Brodman's Areas 44 and 45 (towards the front of the brain and slightly to the side) in the left hemisphere are responsible for speech production. The researchers used magnetic waves to reduce the activity of the corresponding area on the right hemisphere, to see if this had any effect on the subjects' stuttering, using percentage of syllables stuttered as a measuring stick. Stimulation of a certain part of the right BA45 seems to have caused a change in speech fluency, suggesting that that area may play a role in stuttering. ​ Should be noted that, since this is only an abstract, we are missing some critical info such as sample size, methods, and which statistical tests were used. There are also a lot of studies that come out like this, suggesting certain areas are responsible for stuttering, but nothing concrete yet. Of course one would hope this is the breakthrough we've all been waiting for, but I wouldn't get my hopes up.