A 35-year-old Army veteran presents with a chief compliant of excessive crying, which he notes is often triggered by thoughts of absence from his family. He reports episodes of often feeling tense and seems to "fly off the handle" more than usual. He explains that prior to these episodes he has bouts of difficulty breathing/shortness of breath. As the PMHNP you know that his symptom of difficulty breathing is theoretically related to activation in what part of the brain?