title: Charting monosynaptic connectivity maps by two-color light-sheet fluorescence microscopy.
abstract: Cellular resolution three-dimensional (3D) visualization of defined, fluorescently labeled long-range neuronal networks in the uncut adult mouse brain has been elusive. Here, a virus-based strategy is described that allowed fluorescent labeling of centrifugally projecting neuronal populations in the ventral forebrain and their directly, monosynaptically connected bulbar interneurons upon a single stereotaxic injection into select neuronal populations. Implementation of improved tissue clearing combined with light-sheet fluorescence microscopy permitted imaging of the resulting connectivity maps in a single whole-brain scan. Subsequent 3D reconstructions revealed the exact distribution of the diverse neuronal ensembles monosynaptically connected with distinct bulbar interneuron populations. Moreover, rehydratation of brains after light-sheet fluorescence imaging enabled the immunohistochemical identification of synaptically connected neurons. Thus, this study describes a method for identifying monosynaptic connectivity maps from distinct, virally labeled neuronal populations that helps in better understanding of information flow in neural systems.
authors.affiliation: Department of Molecular Neuroscience, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Niedworok
authors.forename: Inna
authors.initials: I
authors.lastname: Schwarz
authors.forename: Julia
authors.initials: J
authors.lastname: Ledderose
authors.forename: Günter
authors.initials: G
authors.lastname: Giese
authors.forename: Karl-Klaus
authors.initials: KK
authors.lastname: Conzelmann
authors.forename: Martin K
authors.initials: MK
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D000229:Dependovirus / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007395:Interneurons / Q000473:pathology; D008027:Light; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods*; D009415:Nerve Net / Q000033:anatomy & histology*; D009830:Olfactory Bulb / Q000033:anatomy & histology; D011820:Rabies virus / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D014764:Viral Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins