O LFACTORY CIRCUITS OF ALL ANIMALS FACE A COMMON CHALLENGE OF

extracting meaningful odor cues from background odors. In this chapter, we summarize what we have learned from our ongoing efforts toward the goal of understanding how the neural circuits in a moth's antennal lobe (AL) determine diverse physiological responses that ultimately mediate the animal's natural behavior. We describe the different types of cellular elements that participate in the glomerular circuitry, focus on the functional organization of these elements, and attempt to explain observed physiological responses in the context of behavior using the understood operating principles of the AL circuits. For convenience, we describe the connections from the perspective of the main output neurons of the circuitry: uniglomerular projection neurons (uPNs).