A goal of this part is to examine the functional impact of catecholaminergic systems on CNS function as it relates to normal and pathological states. The participants achieve their objectives individually by relating their high-quality work on this expansive topic, while maintaining a focus on the functional implications of their findings. Nonetheless, despite the necessarily broad nature of the topics presented, there is a remarkable degree of convergence of information. Several subthemes have emerged as a consequence of considering this work in its entirety. First is the importance of examining neurotransmitter effects, not in isolation, but in terms of interactions with other neurotransmitter systems. History has shown that a limited focus often produces confusing or inconsistent results, which become increasingly clear on consideration of the state of the organism. Second is the importance of examining pharmacological and pathophysiological interactions in light of the anatomy of the system and how developmental influences can alter this relationship. Such very general considerations have been found to provide an essential ingredient in understanding the nature of catecholamine function within this complex system.