Figure 3. Efficiency of ChR2-expressing piriform neurons in eliciting conditioned behavior.

A. Relationship between the number of ChR2-expressing neurons and incidence of flight behavior in the aversive conditioning paradigm. The number of ChR2⁺ neurons was determined and correlated with the percentage of trials in which animals exhibited flight behavior for mice expressing ChR2 using the dual virus strategy.

B. Relationship between the number of ChR2-expressing neurons and distance traveled in the aversive conditioning paradigm. Same animals as in A.

C. Spatial distribution of conditioned ensembles. The centers of ChR2-expressing ensembles are mapped on a schematic showing the borders of the piriform cortex for mice expressing ChR2 using the dual virus strategy and trained in the aversive conditioning behavioral paradigm. The borders of the piriform were drawn by referring to the Paxinos atlas. Only animals with > 300 ChR2⁺ neurons are included. Percent flight behavior for each injection site is documented in Table S1.

D. Comparison of the number of CS-US pairings required for the onset of flight behavior in response to the CS alone in the aversive conditioning paradigm when the CS was either an odorant (N=4) or photostimulation of ChR2⁺ neurons (hSynapsin1: N=2, Emx1: N=2, Dual Virus with >300 ChR2⁺ neurons: N=7).

E. Comparison of the number of blocks of trials required to reach a fraction of correct licks (# of licks following CS⁺ / total # of licks) exceeding 0.7 for two consecutive blocks in the appetitive go/no go discrimination assay when the CS was either an odorant (N=6) or photostimulation of ChR2⁺ neurons (Dual Virus with >300 ChR2⁺ neurons: N=6).