Octopamine modulates activity of neural networks in the honey bee antennal lobe

• Published in: Journal of Comparative Physiology Vol. 199; no. 11; pp. 947 - 962
• Main Authors: Rein, Julia, Mustard, Julie A, Strauch, Martin, Smith, Brian H, Galizia, C. Giovanni
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.11.2013; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Adrenergic alpha-Agonists - pharmacology; Animal Physiology; Animals; antennal lobe; Apis mellifera; Arthropod Antennae - cytology; Bees; Biomedical and Life Sciences; calcium; Calcium - metabolism; Dose-Response Relationship, Drug; Drosophila; Fura-2 - analogs & derivatives; Fura-2 - metabolism; Gene Expression Regulation - drug effects; honey bees; image analysis; Insect Proteins - genetics; Insect Proteins - metabolism; learning; Life Sciences; Nerve Net - drug effects; neural networks; neurons; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Neurosciences; octopamine; Octopamine - pharmacology; odor compounds; Odorants; odors; Original Paper; plastics; Principal Component Analysis; receptors; Receptors, Biogenic Amine - genetics; Receptors, Biogenic Amine - metabolism; RNA interference; Time Factors; Zoology; Calcium imaging; Insects; Octopamine; Olfaction; Plasticity
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-013-0805-y

Neuronal plasticity allows an animal to respond to environmental changes by modulating its response to stimuli. In the honey bee (Apis mellifera), the biogenic amine octopamine plays a crucial role in appetitive odor learning, but little is known about how octopamine affects the brain. We investigated its effect in the antennal lobe, the first olfactory center in the brain, using calcium imaging to record background activity and odor responses before and after octopamine application. We show that octopamine increases background activity in olfactory output neurons, while reducing average calcium levels. Odor responses were modulated both upwards and downwards, with more odor response increases in glomeruli with negative or weak odor responses. Importantly, the octopamine effect was variable across glomeruli, odorants, odorant concentrations and animals, suggesting that the octopaminergic network is shaped by plasticity depending on an individual animal’s history and possibly other factors. Using RNA interference, we show that the octopamine receptor AmOA1 (homolog of the Drosophila OAMB receptor) is involved in the octopamine effect. We propose a network model in which octopamine receptors are plastic in their density and located on a subpopulation of inhibitory neurons in a disinhibitory pathway. This would improve odor-coding of behaviorally relevant, previously experienced odors.