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How does an animal ensure that an appropriate motor action is expressed at the right time?

Similar to humans Drosophila larvae and flies use past experience to predict the future, be it the consequence of an animal’s own actions or upcoming external events. These predictions then can contribute to the selection of behaviour which is in addition under motivational control. The mechanisms of motivational control have been widely studied; however the molecular and neuronal basics remain rather unknown.

Drosophila is an ideal model to investigate this issue as well-established learning paradigms exist. One prominent paradigm that is used in flies and larvae uses learned representations of olfactory cues associated with food. Hereby activation of the neuropeptide F (NPF) was shown to mimic food deprivation and promotes memory performance in satiated flies. As larvae are constant feeders and therefore differ in their naïve food-seeking behaviour to flies we investigated the action of NPF in larval associative olfactory learning by spatio-temporal decrease and increase of the peptidergic NPF signalling. In contrast to adult behaviour larval learning performance decreased with higher NPF levels, suggesting a different function of NPF in the larval brain.