The locus ceruleus norepinephrine system

Abstract

The LC is a cluster of NE-containing neurons located in the upper dorsolateral pontine tegmentum (figure 1). These neurons have extensively branched axons that project throughout the neuraxis and provide the sole source of NE to the neocortex, hippocampus, cerebellum, and most of the thalamus.^1,2 Despite its widespread distribution, noradrenergic innervation shows regional specificity. For example, brain areas involved in spatial attention (such as the prefrontal and parietal cortices) receive particularly dense LC-NE inputs. In general, individual LC neurons send axon collaterals to multiple targets that process the same sensory information. Norepinephrine is released both at typical synapses and at nonsynaptic release sites; extrasynaptic NE mediates paracrine effects on neurons, glial cells, and microvessels.^1–4,8