Raphe nuclei
Figure 7.3. The raphe nuclei are located along the midline of the brainstem.
Serotonergic axons from the raphe nuclei innervate the entire brain.The total number of serotonergic neurons in the human brain may
be on the order of only a hundred thousand or so cells, but these neu-
rons likely have an impact on billions of other cells by way of highly
branched axons extending throughout the brain.
The monoamine neurotransmitters dopamine, norepinephrine,
and epinephrine are made from the (essential) amino acid phenylala-
nine (Fig. 7.4). Norepinephrine and epinephrine also go by the names
noradrenaline and adrenaline, respectively. The different names
derive from different root words for “next to the kidney” (Greek epi
- nephros, Latin ad + renal), the location of the adrenal gland, where
these molecules were first identified.