Integration of the olfactory code across dendritic claws of single mushroom body neurons

• Published in: Nature neuroscience Vol. 16; no. 12; pp. 1821 - 1829
• Main Authors: Gruntman, Eyal, Turner, Glenn C
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.12.2013; Nature Publishing Group
• Subjects: 631/378/2624/1704; Animal Genetics and Genomics; Animals; Animals, Genetically Modified; Behavioral Sciences; Biological Techniques; Biomedicine; Calcium - metabolism; Cells; Dendrites - physiology; Drosophila; Drosophila Proteins; Electric Stimulation; Female; Insects; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Membrane Potentials - drug effects; Membrane Potentials - genetics; Membrane Potentials - physiology; Models, Neurological; Morphology; Mushroom Bodies - cytology; Neurobiology; Neurons; Neurons - cytology; Neurosciences; Odorants; Odors; Olfactory cortex; Olfactory Pathways - physiology; Patch-Clamp Techniques; Photic Stimulation; Physiological aspects; Rhodopsin - genetics; Rhodopsin - metabolism; Structure; Synapses - physiology; United States; New York; United States > US
• ISSN: 1097-6256; 1546-1726
• DOI: 10.1038/nn.3547

The authors use dendritic imaging to examine odor response properties of individual synaptic sites of mushroom body neurons. They find that mushroom body neurons receive input from different glomerular channels and require several of those inputs to be co-active to spike, a likely foundation for their remarkable stimulus selectivity. In the olfactory system, sensory inputs are arranged in different glomerular channels, which respond in combinatorial ensembles to the various chemical features of an odor. We investigated where and how this combinatorial code is read out deeper in the brain. We exploited the unique morphology of neurons in the Drosophila mushroom body, which receive input on large dendritic claws. Imaging odor responses of these dendritic claws revealed that input channels with distinct odor tuning converge on individual mushroom body neurons. We determined how these inputs interact to drive the cell to spike threshold using intracellular recordings to examine mushroom body responses to optogenetically controlled input. Our results provide an elegant explanation for the characteristic selectivity of mushroom body neurons: these cells receive different types of input and require those inputs to be coactive to spike. These results establish the mushroom body as an important site of integration in the fly olfactory system.