Electrical Coupling between Olfactory Glomeruli

• Published in: Neuron (Cambridge, Mass.) Vol. 67; no. 6; pp. 1034 - 1047
• Main Authors: Yaksi, Emre, Wilson, Rachel I.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.09.2010; Elsevier Limited
• Subjects: Animals; Animals, Genetically Modified; Antagonists; Cadmium Chloride - pharmacology; CD8 Antigens - genetics; CD8 Antigens - metabolism; Connexins - genetics; Drosophila; Drosophila Proteins - genetics; Electric Stimulation - methods; Electrical Synapses - physiology; Eukaryotic Initiation Factor-5 - genetics; Experiments; Female; gamma-Aminobutyric Acid - metabolism; Light; Luminescent Proteins - genetics; Models, Biological; Mutation - genetics; Nerve Tissue Proteins - genetics; Neural Inhibition - genetics; Neurons; Neuropil - cytology; Neuropil - drug effects; Neuropil - physiology; Odorants; Olfactory Receptor Neurons - drug effects; Olfactory Receptor Neurons - physiology; Patch-Clamp Techniques - methods; Rhodopsin - genetics; Rhodopsin - metabolism; Sense Organs - cytology; Smell - drug effects; Smell - genetics; Smell - physiology; Software; Studies; Synaptic Transmission - drug effects; Synaptic Transmission - genetics
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2010.08.041

In the Drosophila antennal lobe, excitation can spread between glomerular processing channels. In this study, we investigated the mechanism of lateral excitation. Dual recordings from excitatory local neurons (eLNs) and projection neurons (PNs) showed that eLN-to-PN synapses transmit both hyperpolarization and depolarization, are not diminished by blocking chemical neurotransmission, and are abolished by a gap-junction mutation. This mutation eliminates odor-evoked lateral excitation in PNs and diminishes some PN odor responses. This implies that lateral excitation is mediated by electrical synapses from eLNs onto PNs. In addition, eLNs form synapses onto inhibitory LNs. Eliminating these synapses boosts some PN odor responses and reduces the disinhibitory effect of GABA receptor antagonists on PNs. Thus, eLNs have two opposing effects on PNs, driving both direct excitation and indirect inhibition. We propose that when stimuli are weak, lateral excitation promotes sensitivity, whereas when stimuli are strong, lateral excitation helps recruit inhibitory gain control. ► Antennal lobe local neurons make electrical synapses onto projection neurons ► These connections are abolished by a mutation in a gap-junction subunit ► This mutation eliminates odor-evoked lateral excitation ► Eliminating this electrical network alters signals sent to higher brain regions