The honeybee as a model for understanding the basis of cognition

Honeybees with their tiny brains exhibit complex social and navigational behaviours and possess a relatively rich cognitive repertoire. A unique feature of honeybee behaviour is the waggle dance, a ritualized movement that communicates locations and their properties.The honeybee brain consists of ∼1 million neurons that are structured in highly ordered neuropils. Many of the central neurons are individually identifiable and some of them are registered in a three-dimensional virtual standard brain atlas.Cognitive forms of learning in the bee include categorization, extraction of dependences on context, sequences and combinations, and evaluation of sequential reward values.The search for neural correlates of learning and memory processing in the honeybee is facilitated by a highly versatile behavioural paradigm: the classical conditioning of the proboscis extension response. This paradigm allows the monitoring of neural events in defined neural networks and single neurons together with behavioural change.Learning-related plasticity is found in all neural components of the olfactory pathway and in an identified reward neuron. The sparse and combinatorial code of odours is predominantly enhanced for the learned odour at the input site of the mushroom body, whereas the mushroom body output codes the value of the learned signals.Memory as characterized by behavioural and molecular studies is processed in four distinct phases in honeybees, which is similar to common properties of memory in other animal species.