Nucleus · one in each half of the brain
Locus coeruleus
Also called LC, Blue spot
The "blue spot": a tiny cluster that sets how alert and ready for action you are.
The locus coeruleus is a tiny cluster of cells in the pons whose name means "blue spot". It is the brain's main source of noradrenaline, a chemical that wakes the brain up. Although it is tiny, it sends fibers to almost the entire brain and spinal cord. It raises alertness, sharpens attention and kicks in during fight-or-flight moments.
Where it is
Deep in the upper pons, one on each side, near the floor of the fourth ventricle, a fluid-filled space in the brainstem.
What it does
Waking and alertness
It is most active when you are awake, is held back during sleep, and goes almost quiet during dream sleep.
Fight or flight
In danger or stress it bursts into action, flooding the brain with noradrenaline so you are ready to react.
Focus
It helps you lock on to what matters.
Memory for big moments
Its noradrenaline helps strengthen memories of exciting or scary events.
Think of it as the brain's dimmer switch for alertness: turned low you feel drowsy, turned up you feel sharp, and turned all the way up you are on high alert.
Works with
- NoradrenalineThis is the chemical it makes and broadcasts across the brain.
- Noradrenaline neuronIt is made of these noradrenaline-releasing nerve cells.
- Prefrontal cortexIts signals tune the focus and alertness of this planning region.
- AmygdalaIt sends noradrenaline to the amygdala, helping mark scary moments as important.
- HippocampusIt helps the hippocampus store vivid memories of emotional events.
- Spinal cordIts fibers even reach down into the spinal cord.
When it goes wrong
Alzheimer's disease
Its cells are damaged in Alzheimer's disease, and studies suggest their loss may help the disease along.
Anxiety and PTSD
An overactive locus coeruleus is linked to anxiety, panic and the constant on-edge feeling of post-traumatic stress.
Opioid withdrawal
Opioids quiet it down. When they are stopped suddenly, it rebounds into overdrive, causing much of the sweating, racing heart and sleeplessness of withdrawal.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- Its cells are also lost in Parkinson's disease, often early on.
Where the name comes from
Latin for "blue spot" or "blue place", after the color of this small patch. Like the substantia nigra, its cells hold a dark pigment called neuromelanin.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the locus coeruleus?
Show the answer
Waking and alertness. It is most active when you are awake, is held back during sleep, and goes almost quiet during dream sleep.
Waking and alertness. It is most active when you are awake, is held back during sleep, and goes almost quiet during dream sleep.
The locus coeruleus is part of which larger structure?
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Pons. It belongs to the pons.
Pons. It belongs to the pons.
Which part fits this description? "Like the brain's dimmer switch for alertness: turned low you feel drowsy, turned up you feel sharp, and turned all the way up you are on high alert."
Show the answer
Locus coeruleus. It is the locus coeruleus. The "blue spot": a tiny cluster that sets how alert and ready for action you are.
Locus coeruleus. It is the locus coeruleus. The "blue spot": a tiny cluster that sets how alert and ready for action you are.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Locus Coeruleus, StatPearls, NCBI Bookshelf
- Neuroanatomy, Reticular Activating System, StatPearls, NCBI Bookshelf
- Opioid Withdrawal, StatPearls, NCBI Bookshelf
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