A presynaptic gain control mechanism fine-tunes olfactory behavior.
Early sensory processing can play a critical role in sensing environmental cues. We have investigated the physiological and behavioral function of gain control at the first synapse of olfactory processing in Drosophila. Olfactory receptor neurons (ORNs) express the GABA(B) receptor (GABA(B)R), and its expression expands the dynamic range of ORN synaptic transmission that is preserved in projection neuron responses. Strikingly, each ORN channel has a unique baseline level of GABA(B)R expression. ORNs that sense the aversive odorant CO(2) do not express GABA(B)Rs and do not have significant presynaptic inhibition. In contrast, pheromone-sensing ORNs express a high level of GABA(B)Rs and exhibit strong presynaptic inhibition. Furthermore, pheromone-dependent mate localization is impaired in flies that lack GABA(B)Rs in specific ORNs. These findings indicate that different olfactory receptor channels employ heterogeneous presynaptic gain control as a mechanism to allow an animal's innate behavioral responses to match its ecological needs.
Root
Cory M
CM
Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Masuyama
Kaoru
K
Green
David S
DS
Enell
Lina E
LE
Nässel
Dick R
DR
Lee
Chi-Hon
CH
Wang
Jing W
JW
D000818:Animals; D030801:Animals, Genetically Modified; D001522:Behavior, Animal / Q000502:physiology*; D029721:Drosophila Proteins / Q000502:physiology; D004331:Drosophila melanogaster; D005260:Female; D009833:Olfactory Pathways / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D017729:Presynaptic Terminals / Q000502:physiology*; D018080:Receptors, GABA-B / Q000502:physiology; D012903:Smell / Q000502:physiology*
D029721:Drosophila Proteins; D018080:Receptors, GABA-B