Diagrammatic representation of the anatomic substrate for the metabolic actions of NE and VIP. VIP, VIP-containing bipolar neuron; NA, noradrenergic afferent; Pyr, pyramidal cell furnishing major efferent projection; SA, specific afferent (i.e., from thalamus or from other cortical areas); WM, subcortical white matter. Cortical layers denoted in roman numerals. Note the tangential orientation of NA fibers and the radially restricted domain of VIP-containing neurons. From ref. 33.