Rafe nuclei: what they are and what function they have in the brain

Serotonin is a brain neurotransmitter strongly involved in emotional regulation and aggressive behavior. The cores of the Rafe, Located in the brainstem, is the area with the most serotonin in the brain and where it is secreted.

In this article, we will know in detail these nuclei at the anatomical level, their functions and how serotonin affects our behavior.

    What are the cores of the Rafe?

    The word “Rafe” comes from the Greek and refers to a ridge that separates two symmetrical areas of an organ or tissue. The nucleus or nuclei of the Rafe is a collection of groups of neurons located in the midline of the brainstem.

    More specifically, Rafe nuclei are a region of the human brain where serotonin, a brain neurotransmitter having an inhibitory effect on the brain, is synthesized and circulated; serotonin acts on receptors located in the amygdala and helps curb aggressive behavior. Its decrease implies an increase in the aggressive response in humans.

    Thus, the serotoninergic system originates in the nuclei of Rafe; these nuclei form a large organized network in the brainstem.

    On the other hand, the cores of the Rafe they are part of the reticular formation, One of the most primitive areas of the brain, responsible for controlling sleep rhythms.

      Where are they?

      Each of the Rafe serotonergic nuclei is located next to the midline of the brainstem. Let’s get to know this area of ​​the brain:

      1. Brainstem

      The nuclei of Rafe are located in the brainstem. The brainstem or stem is the region responsible for human “emotional responses” and includes other structures such as the bridge, cerebellum, reticular formation, and locus coeruleus. In humans, these primitive structures remain active as alert mechanisms vital for survival, but also for maintaining the sleep-wake and breathing cycle.

      The brainstem, in turn, consists of several very important areas such as the midbrain, the bridge and the medulla oblongata. In addition to the above, it is also responsible for the communication of the spinal cord and peripheral nerves with different areas of the brain.

      Functions of nuclei

      As we have seen, the main function of the Rafe nuclei is the synthesis of serotonin, the main neurotransmitter for the proper functioning of the nervous system. Let’s take a look at some of the most important functions of these cores:

      1. Mental regulation: serotonin (SA)

      Serotonin regulates moodAnd it does this by controlling negative emotions such as fear, aggression, or anxiety. On the other hand, its lack or reduction can trigger disorders such as depression.

      Once serotonin is synthesized in Rafe’s nuclei, it is sent to the rest of the nervous system, where it performs its functions. Serotonin maintains and regulates mood and controls certain aggressive behaviors (also in animals). Certain drugs, such as SSRIs (antidepressants), inhibit the reuptake of serotonin, which leads to an increase in its concentration levels in the brain; all of this implies that depressive states improve (i.e. improve mood). This is why they are often used to treat depression (along with other serotonin boosters such as tricyclic antidepressants, MAOIs, etc.).

      On the other hand, you should know that the Rafe nuclei contain another type of neurons, not just serotonergics.

      2. Sleep-wake cycles

      The cores of the Rafe also ithey participate in the regulation of sleep-wake cycles, Working synchronously with the hypothalamus, with which they will provide feedback on alert and wakeful levels, thus producing more or less serotonin.

      3. Pain inhibition

      In addition, the nuclei of the Rafe (in particular the nucleus magnus and the dorsal nucleus) are involved in the processes of inhibiting pain.

      4. Aggressive behavior

      As we have seen, aggressive behavior is linked to serotonin levels (More serotonin, less aggressive behavior). Many structures are involved in the deployment and control of this behavior, such as the sensory systems (at first), the thalamus (which receives information) and the amygdala (where information culminates).

      Anatomy of Rafe nuclei

      The cores of the Rafe are divided into six small cores. Some of them are located in the rostral area (closer to the upper brainstem area), while others are located in the flow area (the lowest area).

      Specifically, 85% of brain serotonergic neurons are located in the rostral area. This zone is composed of the nucleus of Rafe pontis and the upper central nucleus, in the area of ​​the bridge, and of the nucleus of Rafe dorsalis, in the area of ​​the midbrain.

      All these cores they connect to areas of the brain where higher functions are performed (Like the frontal areas), although neurons in the dorsal nucleus connect to many areas of the brain such as the orbitofrontal cortex or the hypothalamus (the latter controls the functioning of the nervous system, among other functions).

      Bibliographical references:

      • Road, A. (2004). Some interesting aspects of violence and child abuse. Rev Cubana Med Gen Integr; 20 (5-6).
      • Rosenweig, MR; Breedlove, SM; Watson, NV (2005). Psychobiology: an introduction to behavioral, cognitive and clinical neuroscience. Barcelona: Ariel.
      • Carlson, NR (2005). Behavioral physiology. Madrid: Pearson Education.

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