Contribution of Neuropeptide F (NPF) Neurons to Reward in Drosophila Melanogaster

In classical experiments performed by Olds & Milner in 1954, it was shown that rats learn to,perform an operant lever-pressing behavior in order to receive an electric stimulus in specific,brain nuclei, leading to the identification of what we currently know as mammalian "reward,centers" and the discovery that neuronal activation in these brain regions is perceived as,rewarding. For the fruit fly Drosophila melanogaster, it is known that specific subsets of,neurons regulate different forms of reward. However, a more extensive circuit level description,of the fly's reward circuit is missing. Here we present the development of a novel and high,throughput 2-choice assay that employs optogenetic activation of neurons to study reward in,Drosophila. This new system was characterized using activation of Neuropeptide F (NPF),neurons, a known rewarding stimulation. We showed that NPF neurons could be subdivided into,different groups based upon their neuroanatomy and contribution to the NPF neuron activationinduced,preference. Finally, we showed that this preference response is dependent on the activity,of dopamine neurons.