The Locus ceruleus, also spelled locus coeruleus, (Latin for 'the blue bit') is a nucleus in the brain stem (inferior to the cerebellum in the caudal midbrain/rostral pons) apparently responsible for the physiological reactions involved in stress and panic. This nucleus is the major location of neurons that release norepinephrine throughout the brain.
The locus ceruleus is widely studied in relation to clinical depression, panic disorder and anxiety. Some antidepressant medications including Reboxetine, Venlafaxine and Bupropion as well as ADHD medication Atomoxetine are believed to act on neurons in this area. This area of the brain is also intimately involved in REM sleep.
The locus coeruleus receives inputs from a number of other brain regions, primarily:
- Medial prefrontal cortex . The connection is constant, excitatory, and increases in strength with raised activity levels in the subject.
- Nucleus paragigantocellularis . This region integrates autonomic and environmental stimuli.
- Nucleus prepositus hypoglossi . This region is involved in gaze.
- Lateral hypothalamus. This releases orexin which, as well as its other functions, is excitatory in the locus coeruleus.