Figure 3.

Working model of the modulatory events contributing to DNC. A. DNC mechanisms engage long, thin spines with narrow neck segments that confine a minute cytosolic volume to subserve biochemical/electrical compartmentalization. DNC spines emanate from high-order dendrites, including the basal dendrites, as the one shown in layer III of monkey dlPFC (pseudocolored yellow). The spine neck is immunoreactive for PDEA (indicated by green arrowheads, and by green ovals in inset), positioned to regulate cAMP in the spine’s bottleneck. Asterisk marks the spine apparatus. Scale bar, 200 nm. B. A schematic illustration of the Ca⁺²-cAMP signaling events that weaken synaptic efficacy in layer III, long, thin spines. C. A schematic illustration of the Ca⁺²-cAMP signaling events that strengthen synaptic efficacy in layer III, long, thin spines. Please note that nicotinic α7 receptors have been documented on spines in rodent PFC (Duffy et al., 2009), but have not been studied in primate. See text for abbreviations.