Activity-Dependent Plasticity in an Olfactory Circuit

• Published in: Neuron (Cambridge, Mass.) Vol. 56; no. 5; pp. 838 - 850
• Main Authors: Sachse, Silke, Rueckert, Erroll, Keller, Andreas, Okada, Ryuichi, Tanaka, Nobuaki K., Ito, Kei, Vosshall, Leslie B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 06-12-2007; Elsevier Limited
• Subjects: Absorptiometry, Photon; Anatomy & physiology; Animals; Behavior; Behavior, Animal - drug effects; Brain - anatomy & histology; Brain - physiology; Carbon Dioxide - metabolism; Carbon Dioxide - pharmacology; Drosophila; Experiments; Female; Fluorescent Antibody Technique; Insects; Interneurons - drug effects; Interneurons - physiology; MOLNEURO; Neuronal Plasticity - drug effects; Neuronal Plasticity - physiology; Neurons; Neurons, Afferent - physiology; Odorants; Olfactory Pathways - anatomy & histology; Olfactory Pathways - drug effects; Olfactory Pathways - physiology; Smell - drug effects; Smell - physiology; SYSNEURO; Variance analysis; Volumetric analysis; SYSNEURO; MOLNEURO
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2007.10.035

Olfactory sensory neurons (OSNs) form synapses with local interneurons and second-order projection neurons to form stereotyped olfactory glomeruli. This primary olfactory circuit is hard-wired through the action of genetic cues. We asked whether individual glomeruli have the capacity for stimulus-evoked plasticity by focusing on the carbon dioxide (CO
2) circuit in
Drosophila. Specialized OSNs detect this gas and relay the information to a dedicated circuit in the brain. Prolonged exposure to CO
2 induced a reversible volume increase in the CO
2-specific glomerulus. OSNs showed neither altered morphology nor function after chronic exposure, but one class of inhibitory local interneurons showed significantly increased responses to CO
2. Two-photon imaging of the axon terminals of a single PN innervating the CO
2 glomerulus showed significantly decreased functional output following CO
2 exposure. Behavioral responses to CO
2 were also reduced after such exposure. We suggest that activity-dependent functional plasticity may be a general feature of the
Drosophila olfactory system.