Figure 5.

A schematic overview of the aminergic systems. Nuclei of origin are caudal but may relay rostrally. They have few cells with many collaterals providing diffuse innervation of the forebrain. The dopamine system is most rostral, most differentiated, and least diffuse. The cholinergic system is most caudal, least differentiated, and most diffuse. Abbreviations: amyg=amygdala; cing=cingulate cortex; cx=cortex; hip=hippocampus; hyp=hypothalamus; pag=periaqueductal gray; pfc=prefrontal cortex. From McNaughton (2002).