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New techniques and resources for remote control of neuronal activity at single-cell resolution have led to an explosion of research into the behavioral neurogenetics of the memory trace (engram) in the fruit fly Drosophila . The available data suggest that after odor-punishment training, associative and odor-specific engrams are local to a single layer of processing along the olfactory pathway, the presynaptic output terminals of the mushroom body Kenyon cells. At the same time, engrams are distributed across this layer for different mnemonic aspects of such a training event, and for different kinds of training event. This nature of engrams as being local and distributed can be revealed at due resolution in Drosophila – as can the way learned behavior is organized in an outcome-oriented way.

The brain is the organ of behavior organization. It structures the solution to the problem of what to do. This is complicated because usually we cannot be certain which behavior would be relatively the best. These processes, taking place between the moment when an uncertainty between behavioral options is recognized and the actual expression of behavior, we regard as ‘taking a decision.’ Such decision making needs to integrate (1) sensory input, (2) the current status reflecting evolutionary and individual history, (3) the available behavioral options, and (4) their expected outcomes. We focus on the decision to behaviorally express an associative memory trace—or not. After sketching the architecture of the chemobehavioral system in larval Drosophila, we present a working hypothesis of odor–taste associative memory trace formation and then discuss whether outcome expectations contribute to the organization of conditioned behavior. We argue that indeed conditioned olfactory behavior is organized according to its expected outcome, namely toward finding reward or escaping punishment, respectively. Conditioned olfactory behaviors are thus not responsive in nature but, rather, are actions expressed for the sake of the sought-for reward and the attempted relief. In addition to the organization of such outcome expectations, we discuss parametric features (‘axes’) of behavioral tasks that we believe bear upon the decision character of the underlying process and discuss whether these features can be found, or may reasonably be sought for, in larval Drosophila. It is argued that rather than trying to draw a line between behavioral processes that reflect decisions and those that are not, it is more useful to ask how strong the decision character of a given behavioral faculty is?