The Locus Ceruleus is a nucleus located in the brain stem. It is primarily responsible for the body’s responses to panic and stress. Discovered in the year 1700 by Félix Vicq-d’Azyr, the locus ceruleus, which translates to “the blue spot,” was named so because of its cerulean exterior, despite its presence in unstained brain tissue.
Anatomy of the Locus Ceruleus
Located in the dorsal wall of the rostral pons, the locus ceruleus is perched on the fourth ventricle’s lateral floor. As the main hub for noradrenaline synthesis, this most primitive part of the brain is composed of medium-sized neurons pigmented with melanin (thus its color.) Approximately 20,000 to 50,000 neurons can be found in the locus ceruleus.
Like most parts of the brain, the locus ceruleus needs an appropriate amount of sleep in order to function well. If sleep is lacking, it could lead to locus ceruleus hypersensitivity which leads to symptoms such as paranoia and psychosis.
Roles of the Locus Ceruleus
The locus ceruleus performs many functions in the body, such as:
Facilitates learning and memory retention.
As it has been said, the locus ceruleus is in charge for the synthesis of noradrenaline, a neurotransmitter that plays a big role in learning and memory. Not only does it improve cognition, it also results to avoidance learning, wherein an individual learns to steer away from ugly or unpleasant experiences.
Helps the body respond to stress.
The locus ceruleus serves as the ‘pacemaker’ of the brain. Because of the numerous connections of this structure to the other parts of the brain, it plays a big role in the body’s response to stress.
When one is thrust to a stressful situation, or experiences a bad ‘gut feeling,’ the locus ceruleus, alongside other brain regions, respond by secreting norepinephrine. The presence of these substances in the bloodstream then leads to heightened awareness, increased awareness, watchfulness and carefulness. It also modifies the sympathetic nervous system, resulting to pupil dilation, increased blood pressure, to name a few.
Facilitates the body’s avoid/attack response.
In times of fear, the locus ceruleus helps in the activation of the body’s avoid/attack response (or fight-or-flight response). It floods the body with norepinephrine, which makes the individual more aware, careful and watchful. This enables a person to save himself or herself from imminent injury or death.
Suppresses the brain’s pleasure center.
The mind’s pleasure center, the nucleus accumbens, is flushed with dopamine in the event of a sexual encounter, delicious meal, monetary reward or illicit drug. While the activation of locus ceruleus can suppress the reward center, illegal substances can inhibit the locus ceruleus, therefore facilitating the pleasurable feeling associated with the use of prohibited drugs.
Plays a role in depression.
Depression, characterized by low mood levels and aversion to most activities, Locus ceruleus plays a big role in depression, as overactivity of said neurons – or the deficiency of noradrenaline produced by this part of the brain – leads to the aforementioned mental condition.
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