title: Local interneurons and projection neurons in the antennal lobe from a spiking point of view.
abstract: Local computation in microcircuits is an essential feature of distributed information processing in vertebrate and invertebrate brains. The insect antennal lobe represents a spatially confined local network that processes high-dimensional and redundant peripheral input to compute an efficient odor code. Social insects can rely on a particularly rich olfactory receptor repertoire, and they exhibit complex odor-guided behaviors. This corresponds with a high anatomical complexity of their antennal lobe network. In the honeybee, a large number of glomeruli that receive sensory input are interconnected by a dense network of local interneurons (LNs). Uniglomerular projection neurons (PNs) integrate sensory and recurrent local network input into an efficient spatio-temporal odor code. To investigate the specific computational roles of LNs and PNs, we measured several features of sub- and suprathreshold single-cell responses to in vivo odor stimulation. Using a semisupervised cluster analysis, we identified a combination of five characteristic features as sufficient to separate LNs and PNs from each other, independent of the applied odor-stimuli. The two clusters differed significantly in all these five features. PNs showed a higher spontaneous subthreshold activation, assumed higher peak response rates and a more regular spiking pattern. LNs reacted considerably faster to the onset of a stimulus, and their responses were more reliable across stimulus repetitions. We discuss possible mechanisms that can explain our results, and we interpret cell-type-specific characteristics with respect to their functional relevance.
authors.affiliation: Neuroinformatik/Theoretical Neuroscience, Institute of Biology, Freie Universität Berlin, Berlin, Germany;
authors.forename: Anneke
authors.initials: A
authors.lastname: Meyer
authors.forename: C Giovanni
authors.initials: CG
authors.lastname: Galizia
authors.forename: Martin Paul
authors.initials: MP
authors.lastname: Nawrot
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D057506:Arthropod Antennae / Q000294:innervation / Q000502:physiology; D001516:Bees; D007395:Interneurons / Q000145:classification / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000502:physiology*; D009812:Odorants; D012903:Smell / Q000502:physiology*
keywords: Fano factor; cluster analysis; coefficient of variation; electrophysiology; honeybee; olfaction; response latency