Leading Edge Essay Small Brains, Bright Minds

Insect brains are structurally very different from mammalian brains, and yet the basic demands of life are quite similar in both groups of animals. What, where, and how should experience be stored for effective use in the future? How should innate information be combined with acquired information? How do the motivational and evaluating neural systems interact? How does the brain choose among similar behavioral options? All of these questions require analyzing neural circuits in animals as they undertake different behaviors. Neural circuits are composed of a large number of single neurons, each of which has its own specific gestalt, connectivity, and history. Ideally, one would like to track neural events within a network of fully characterized neurons. Insect brains provide us with such an option. Many neurons can be identified at the singlecell level according to their structure, enabling us to trace network properties to single-neuron functions and to understand the working of the network according to the composition of participating neurons. One insect that provides a valuable model system for examining neural pathways and their connection to learning and memory and social behavior is the honeybee (Apis mellifera). Honeybees are social animals and of all insects have the most sophisticated community structure. Like other social animals, they require sophisticated cognitive faculties: They do not survive in isolation, they need to communicate intensively with each other, and they depend on a safe return to their community housing. Navigation during exploratory behavior, mating, and foraging is a result of innate knowledge about celestial compass properties, but these guiding structures need to be related to the environmental features of the home range through learning. In this sense, the honeybee