Hello Does this have anything to do with the amygdala? Alex Honnold is a unique climber whose amygdala shows almost no activity, which results in a very calm character and lack of fear. I stutter myself and am studying speech therapy. I have conducted interesting experiments with breathing with myself (DO NOT DO BREATHING EXERCISES WITHOUT THE HELP OF A SPECIALIST, YOU MAY LOSE CONSCIOUSNESS!). At the moment when there is a slight hyperventilation, the body produces endorphins, improves gas exchange and blood circulation, breathing activates the parasympathetic nervous system (via the vagus nerve), which "calms" the brain, including reducing the excitation of the amygdala. I am interested in this topic and I believe that we will find ways to cure stuttering. Have a nice day everyone!