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. Author manuscript; available in PMC: 2012 Mar 16.
Published in final edited form as: Cell. 2011 Sep 16;146(6):1004–1015. doi: 10.1016/j.cell.2011.07.041

Figure 1. Expression of ChR2 in layer 2 and 3 of piriform cortex after injection with different variants of lentivirus encoding ChR2.

Figure 1

A. Lentivirus carrying ChR2 fused to a fluorescent reporter (XFP = Cherry or EYFP) under control of the hSynapsin1 promoter was stereotactically injected into the piriform. The hSynapsin1 promoter drives ChR2:XFP expression in both excitatory and inhibitory neurons. Coronal sections through the injection site reveal expression of ChR2:XFP (red) in dense populations of layer 2 and 3 piriform neurons. The labeled cells are shown at higher magnification on the right. c-Fos expression after in vivo photostimulation is shown in green. NT = Neurotrace (blue). Scale bars on left = 50 µm and on right =100 µm.

B. Lentivirus carrying ChR2:XFP flanked by loxP sites and under control of the EF1 alpha promoter was injected into the piriform of Emx1-IRES-Cre mice. ChR2:XFP (red) expression is restricted to dense populations of excitatory neurons in these mice.

C. Lentivirus carrying ChR2:EYFP-IRES-nCherry (nuclear Cherry) flanked by loxP sites and under control of the EF1alpha promoter was co-injected into piriform with a second lentivirus carrying the hSynapsin1 promoter driving Cre:EGFP. This dual virus strategy was used to generate sparse labeling of piriform neurons. nCherry (red) labels the cell bodies whereas EYFP (green) labels both cell bodies and processes.

D. c-Fos expression (blue) after in vivo photostimulation for the same animal shown in C.