UC San Diego

Internal physiology has a dramatic effect on animals' natural behavior. We therefore investigated the effect of starvation in shaping olfactory processing in Drosophila. Previous work from our lab has shown that glomeruli in the first olfactory relay are hardwired for attraction and aversion. DM1 glomerular activity signals for attraction to food odor, whereas DM5 glomerular activity triggers aversion. We observed that DM1 glomerular activity increases via presynaptic facilitation while DM5 activity decreases via presynaptic inhibition. DM1 modulation is mediated by short NPF (sNPF) signaling and DM5 modulation is mediated by tachykinin (DTK) signaling. Both of these opposite modulatory mechanisms in DM1 and DM5 are required for the fly's food search behavior. Together, these two different neuropeptide signaling mechanism represents a push-pull mechanism, whereby starvation causes attraction to be enhanced and aversion to be suppressed. This leads to maximal attraction in starved flies and minimal attraction in fed flies