What is the locus coeruleus?

The locus coeruleus, also referred to as the "blue spot," is a structure in the brain filled with neurons that contain norepinephrine, which is akin to adrenaline in the rest of the body. This structure plays a crucial role in how we respond to our environment. For instance, when the locus coeruleus neurons fire in bursts, it enables us to quickly switch our attention to stimuli like sudden loud noises, facilitating rapid learning and response. This aspect is particularly important for our stress response.

Moreover, the locus coeruleus is associated with different levels of alertness throughout the day and night. During normal waking hours, it helps maintain sustained attention. During REM sleep, the locus coeruleus completely shuts off, which is essential for the process of weakening or pruning unnecessary synapses. This is important for clearing out outdated or redundant information and helps with learning new things throughout one's life 1.