Neurobiological theories of panic disorder point to which brain region as the major source of norepinephrine?

1. The locus coeruleus sits in the brainstem and is the major source of norepinephrine in the brain. 2. Norepinephrine triggers the fight-or-flight response, and activation of this region is associated with anxiety and fear. 3. Stimulating it electrically or with drugs produces panic-like symptoms in nonhuman primates, which is why abnormal activity there is a proposed cause. 4. The orbitofrontal cortex is tied to obsessive-compulsive disorder, while the limbic system and prefrontal cortex feature in accounts of schizophrenia. _Source: OpenStax Psychology (1st ed., CC BY 4.0), Ch 15 "Psychological Disorders", section 15.4 Anxiety Disorders_