Rabies virus-mediated connectivity tracing from single neurons

[Display omitted] •Bridging cell physiology and connectomics by monosynaptic tracing from single neurons.•Functionalized, single-cell-initiated mono-transsynaptic tracing.•“Virus stamping” as the latest twist in single cell manipulations in vivo.•Fast and volumetric mapping of monosynaptic circuits at super resolution. An understanding of how the brain processes information requires knowledge of its underlying wiring diagrams, as well as insights into the relationship between circuit architecture and physiological function. Notably, rabies virus based single-cell genetic manipulations that can facilitate an experimental link between physiology and genetics have recently advanced the field of systems neuroscience. It allows capturing the synaptic and the anatomical receptive fields of individual neurons. Recently, the methodological portfolio has been upgraded by two novel approaches, single cell electroporation with genetically encoded Ca2+ sensors allowing for functionalized transsynaptic tracing and single cell targeted virus stamping. Especially the development of virus stamping provides a versatile solution for targeted single-cell infection of diverse cell types with different viruses at once, both in vitro and in vivo. Here we will summarize the latest developments in this rapidly moving field and provide a perspective for automated, quantitative analysis of single cell initiated connectomes.