%0 Journal Article %A Veit Grabe %A Marco Schubert %A Martin Strube-Bloss %A Anja Reinert %A Silke Trautheim %A Sofia Lavista-Llanos %A André Fiala %A Bill S. Hansson %A Silke Sachse %T Odor-Induced Multi-Level Inhibitory Maps in Drosophila %D 2020 %R 10.1523/ENEURO.0213-19.2019 %J eneuro %P ENEURO.0213-19.2019 %V 7 %N 1 %X Optical imaging of intracellular Ca2+ influx as a correlate of neuronal excitation represents a standard technique for visualizing spatiotemporal activity of neuronal networks. However, the information-processing properties of single neurons and neuronal circuits likewise involve inhibition of neuronal membrane potential. Here, we report spatially resolved optical imaging of odor-evoked inhibitory patterns in the olfactory circuitry of Drosophila using a genetically encoded fluorescent Cl- sensor. In combination with the excitatory component reflected by intracellular Ca2+ dynamics, we present a comprehensive functional map of both odor-evoked neuronal activation and inhibition at different levels of olfactory processing. We demonstrate that odor-evoked inhibition carried by Cl- influx is present both in sensory neurons and second-order projection neurons (PNs), and is characterized by stereotypic, odor-specific patterns. Cl--mediated inhibition features distinct dynamics in different neuronal populations. Our data support a dual role of inhibitory neurons in the olfactory system: global gain control across the neuronal circuitry and glomerulus-specific inhibition to enhance neuronal information processing. %U https://www.eneuro.org/content/eneuro/7/1/ENEURO.0213-19.2019.full.pdf