All procedures were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and approved by the Massachusetts Institute of Technology Committee on Animal Care. C57BL/6J E16-timed pregnant mice were used for electroporation. Surgery was done under ketamine-xylazine anesthesia and buprenorphine analgesia. For cortical experiments, DNA solution containing plasmids of interest were injected into lateral ventricle of each embryo using a pulled capillary tube. Five square pulses (50ms width, 1Hz, 35V) were applied using tweezer electrode for electroporation (Harvard Apparatus, ECM 830). Direct opsin-expressing experimental mice were electroporated with pCAG-opsin-GFP plasmid. Post-synaptic experimental mice were electroporated with pCAG-FLEX-rc[Chronos-GFP] and/or pCAG-FLEX-Chrimson-mOrange2, and pCAG-Cre plasmids. pCAG-Chrimson-tdTomato was additionally used in half of the single post-synaptic experiments.
For the retinal ganglion cell-superior colliculus experiment, intravitreal virus injection was performed on P0 C57BL/6 mice with Nanoject II (Drummond) under cold anesthesia. 100 nL of rAAV2/8-Synapsin-Chronos-GFP (titer 1.4×1013 particles/mL) was injected into the eye. AAV particles were produced by the University of North Carolina Chapel Hill Vector Core.
For the retinal ganglion cell-superior colliculus experiment, intravitreal virus injection was performed on P0 C57BL/6 mice with Nanoject II (Drummond) under cold anesthesia. 100 nL of rAAV2/8-Synapsin-Chronos-GFP (titer 1.4×1013 particles/mL) was injected into the eye. AAV particles were produced by the University of North Carolina Chapel Hill Vector Core.
