Figure 5

A schematic summary of the proposed roles of DM-NPF and DL2 neurons in food odor perception and feeding motivation. The model depicts a module of a food odor processing circuit in the larval brain hemisphere comprising four DL2 and a downstream DM-NPF. We posit that the DM-NPF neuron defines the highest-order processing module in the circuit. In the lateral horn, the DM-NPF neuron receives ascending presynaptic DA signals encoding appetitive odor representations. Furthermore, the DM-NPF neuron relays descending signals to NPFR1 neurons in the SEZ that control peripheral targets (Fig. S1). Our previous study showed that the appetitive response of fed larvae with reduced Dop1R1 activity in NPF neurons required odor stimuli that are higher than those normally required, as evidenced by a right-shift in the dose-response curve of fed larvae². Together, these findings support the notion that a Dop1R1-mediated intracellular mechanism in the DM-NPF neuron may restrict its responses to selected DA signals, thereby discriminatively assigning appetitive salience to such DA signals. ORNs: olfactory receptor neurons; PNs: projection neurons; DANs: a subset of DA neurons named DL2-1 to 4⁷; NPFN: DM-NPF neuron; NPFRNs: NPFR1 neurons; KC: Kenyon cells; AL: antenna lobes; LH: lateral horns; SEZ: subesophageal zone; AN: antenna nerve; DOG: dorsal organ ganglia; DO: dorsal organ.