Here’s a few studies which explain how the dopamine receptors in the brain help regulate muscle tone. Personally, I think this helps explain, at least in my case, my combination of cloudy head and cognition with my muscle issues (combined with other askew things, of course).
nature.com/npp/journal/v25/n … 5688a.html
"The current findings provide new information about motor control by demonstrating that antagonism of both D1 and D2 receptors in functionally defined striatal sites play a key role in the regulation of muscle tone. "
pubmedcentral.nih.gov/articl … rtid=42581
“These findings provide evidence that dopamine receptors in the substantia nigra play an important role in the regulation of muscle tone.”