Adaptive Expansion of Taste Neuron Response Profiles by Congruent Aroma in Drosophila

Abstract

Pairing of food aroma with selected taste can lead to enhanced food flavor and eating euphoria, but how cross-modal sensory combinations are integrated to increase food reward value remains largely unclear. Here we report that combined stimulation by a banana-like scent and glucose drastically increased appetite in well-nourished Drosophila larvae, and the appetizing effect involves a previously uncharacterized smell-taste integration process at axon terminals of two Gr43a gustatory neurons. Molecular genetic analyses of the smell-taste integration reveal a G protein-mediated tuning mechanism in two central neuropeptide F (NPF) neurons. This mechanism converts selected odor stimuli to NPF-encoded appetizing signals that potentiate Gr43a neuronal response to otherwise non-stimulating glucose. Further, NPF potentiated glucose response requires a Gr43a-independent pathway involving an NPF receptor (NPFR1) and neuropeptide effector DH44. Our finding of adaptive expansion of taste neuron response profiles by congruent aroma reveals a previously uncharacterized layer of neural complexity in food flavor perception.

Keywords: sensory integration, dopamine, NPF, neuropeptide, feeding, food reward, Drosophila