Kara L. Agster, Carlos A. Mejias-Aponte, Brian D. Clark and Barry D. Waterhouse
The conventional view has been that norepinephrine (NE)-containing projections from the locus coeruleus (LC) are uniform across the cortical mantle. Although NE fiber density may be equivalent among regions, the density of NE varicosities is not uniform. We found that NE varicosities are greater in the prefrontal cortex than in the motor, somatosensory, or piriform cortices. This suggests that activation of the LC may produce a differential release of NE across the cortex, with the greatest amounts of NE released within the prefrontal cortex.