Brainstem Circuitry and Emotions
Abstract The human brainstem forms the central axis of the brain and serves as an integrative hub for major critical processes for the individual's survival and homeostasis. Extending within the brainstem's tegmentum and basal forebrain, the reticular formation constitutes a subcortical network of diffusely arranged nuclei projecting throughout the entire central nervous system. These include the noradrenergic locus ceruleus in the pons; the serotonergic dorsal raphe nucleus and dopaminergic substantia nigra in the midbrain; and the cholinergic nucleus basalis of Meynert in the basal forebrain. Here we review the neuroanatomical and functional properties of the reticular formation and provide evidence demonstrating its crucial role in mediating neuropsychiatric functions including sleep homeostasis and mood disorders. Overall, a better understanding of the reticular formation properties and vulnerability in brain disorders will provide the necessary foundation for the development of therapies targeting these systems.