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Hopp, Elisabeth (2015): Subcellular mapping of dendritic activity in optic flow processing neurons. Dissertation, LMU München: Faculty of Biology



Dendritic integration is a fundamental element of neuronal information processing. So far, few studies have provided a detailed picture of this process, describing the properties of local dendritic activity and its subcellular organization. Here, I used 2-photon calcium imaging in optic flow processing neurons of the blowfly Calliphora vicina to determine the preferred location and direction of local motion cues for small branchlets throughout the entire dendrite. I found a pronounced retinotopic mapping on both the subcellular and the cell population level. In addition, dendritic branchlets residing in different layers of the neuropil were tuned to distinct directions of motion. Within one layer, local preferred directions varied according to the deflections of the ommatidial lattice. Summing the local receptive fields of all dendritic branchlets reproduced the characteristic properties of these neurons’ axonal output receptive fields. These results corroborate the notion that the dendritic morphology of vertical system cells allows them to selectively collect local motion inputs with particular directional preferences from a spatially organized input repertoire, thus forming filters that match global patterns of optic flow. These data illustrate a highly structured circuit organization as an efficient way to hard-wire a complex sensory task.