Question

What is the Locus Coeruleus and what does it have to do with ADHD?

Answer 1

The locus coeruleus, a small nucleus located in the pons, is the main source of noradrenaline in the forebrain. LC is the primary site of norepinephrine production in the brain. The nucleus sends norepinephrine throughout the cerebral cortex as well as to a variety of other structures including the amygdala, hippocampus, cerebellum, and spinal cord. In fact, the LC sends projections to virtually all brain regions except the basal ganglia, which seems to be lacking noradrenergic (i.e.noradrenaline/norepinephrine-related) input.

It is a nucleus in the brain stem involved with physiological responses to stress and panic.

The projections of this nucleus reach far and wide. For example, they innervate the spinal cord, the brain stem,
cerebellum, hypothalamus, the thalamic relay nuclei, the amygdala, the basal telencephalon, and the cortex. The norepinephrine from the LC has an excitatory effect on most of the brain, mediating arousal and priming the brain’s neurons to be activated by stimuli.
As an important homeostatic control center of the body, the locus coeruleus receives afferents from the
hypothalamus. The cingulate gyrus and the amygdala also innervate the LC, allowing emotional pain and stressors to trigger noradrenergic responses. The cerebellum and afferents from the raphe nuclei also project to the LC,particularly the raphe pontis and raphe dorsalis.
The locus coeruleus receives inputs from a number of other brain regions, primarily:
• Medial prefrontal cortex, whose connection is constant, excitatory, and increases in strength with raised activity levels in the subject.
• Nucleus paragigantocellularis, which integrates autonomic and environmental stimuli.
• Nucleus prepositus hypoglossi, which is involved in gaze.
• Lateral hypothalamus, which releases orexin, which, as well as its other functions, is excitatory in the locus
coeruleus.

2. The LC may figure in 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.

Norepinephrine has been shown to play a role in a person's mood and ability to concentrate. Low levels of norepinephrine may lead to conditions such as attention deficit hyperactivity disorder (ADHD), depression, and hypotension (very low blood pressure). Norepinephrine controls by LC.