Monosynaptic rabies virus tracing from projection-targeted single neurons

A single neuron integrates inputs from thousands of presynaptic neurons to generate outputs. Circuit tracing using G-deleted rabies virus (RVAG) vectors permits the brain-wide labeling of presynaptic inputs to targeted single neurons. However, the experimental procedures are complex, and the success rate of circuit labeling is low because of the lack of validation to increase the accuracy and efficiency of monosynaptic RVAG tracing from targeted single neurons. We established an efficient RVAG tracing method from projection target-defined single neurons using TVA950, a transmembrane isoform of TVA receptors, for initial viral infection. Presynaptic neurons were transsynaptically labeled from 80 % of the TVA950-expressing single starter neurons that survived after infection with EnvA-pseudotyped RVAG in the adult mouse brain. We labeled single neuronal networks in the primary visual cortex (V1) and higher visual areas, namely the posteromedial area (PM) and anteromedial area (AM), as well as the single neuronal networks of PM-projecting V1 single neurons. Monosynaptic RVAG tracing from projection-targeted single neurons revealed the input-output organization of single neuronal networks. Single-neuron network analysis based on RVAG tracing will help dissect the heterogeneity of neural circuits and link circuit motifs and large-scale networks across scales, thereby clarifying information processing and circuit computation in the brain.

Automated summary

The study established an efficient RVAG tracing method to label the input-output organization of single neuronal networks, aiding in analyzing the heterogeneity of neural circuits and revealing information processing and circuit computation in the brain.