NETTER - Neuroscience Flash Cards

Serotonergic Pathways
1. Cingulum bundle
2. Basal ganglia
3. Thalamus
4. Ascending serotonergic
pathway
5. Nucleus raphe dorsalis
6. Nucleus centralis superior
7. Nucleus raphe pontis
8. Nucleus raphe magnus
9. Nuclei raphe pallidus and
obscurus
10. Descending serotonergic
pathway
Comment: Serotonergic (5-hydroxytryptamine, 5-HT) neurons
are found in the raphe nuclei of the brain stem and adjacent wings
of cells in the reticular formation; these neurons have widespread
connections that innervate every major subdivision in the CNS,
providing a parallel to many, but not all, of the projections of the
noradrenergic (NA) system. Rostral 5-HT neurons in the nuclei
raphe dorsalis and centralis superior project rostrally to innervate
the cerebral cortex, many limbic forebrain structures (hippocampal
formation, amygdala), basal ganglia, many hypothalamic nuclei
and areas, and some thalamic regions. Caudal 5-HT neurons in
nuclei raphe pontis, magnus, pallidus, and obscurus project more
caudally to innervate many regions of the brain stem, cerebellum,
and spinal cord. Nucleus raphe magnus projections to the dorsal
horn of the spinal cord markedly enhance opiate analgesia and
alter pain processing. The ascending 5-HT systems help regulate
emotional behavior and wide-ranging hypothalamic and limbic
functions (neuroendocrine, visceral/autonomic), similar to their
NA counterparts. 5-HT neurons are involved in sleep-wakefulness
cycles and, similar to locus coeruleus NA neurons, stop firing during
REM sleep. 5-HT projections to the cerebral cortex modulate the
processing of afferent inputs, such as those from the visual cortex.
Descending 5-HT neurons modulate preganglionic autonomic and
lower motor neuron activity. Many pharmacological agents target
5-HT neurons and their receptors, including drugs for treating
depression; other cognitive, emotional, and behavioral states;
headaches; pain; movement disorders; and others.
Regional Neuroscience See book 13.32