Sure. [This one](http://www.academia.edu/download/49841674/Increased_dopamine_activity_associated_w20161024-15662-ivsfvf.pdf) demonstrates the correlation between dopamine and stuttering. [This one](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775364/#S12title) explains how dopamine affects speech planning, leading to stuttering/blocks, but it's a lot more technical. I'm currently working on the the neuroscience chapter of the book. I'll probably post a draft of it to r/stutter when it's halfway readable. Might be at least a month, though.