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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 2. Ensembles of ChR2-expressing piriform neurons entrained to elicit aversive behavior.

Figure 2

A. Schematic of the apparatus used for the aversive conditioning paradigm. During training, photostimulation of ChR2-expressing neurons in piriform, the conditioned stimulus (CS), was paired with foot shock, the unconditioned stimulus (US), applied only on the side of the arena where the animal was located at the time of photostimulation. The animals escaped foot shock by running to the opposite side.

B. The percentage of trials in which animals exhibited flight behavior in response to the CS alone during the testing phase. hSynapsin1 = ChR2 expression driven from the human Synapsin1 promoter (N=7); Emx1 = ChR2 expression driven by the Emx1 promoter (N=4); Dual Virus = ChR2 expression generated by co-infection of Cre and Cre-dependent ChR2 viruses (animals with > 300 ChR2+ neurons, N=10); (−) Virus = no viral injection (N=3); EGFP = virus encoding EGFP but not ChR2 was injected into piriform (N=6); (−) Photostimulation = ChR2 expression driven by the hSynapsin1 promoter without photostimulation during training (N=3); Unpaired CS/US = ChR2 expression was driven from the human Synapsin1 promoter but foot shock application was not contingent upon photostimulation (i.e., equal numbers of CSs and USs were presented in random order with delays always exceeding 1 minute, N=4); Reversed CS/US = ChR2 expression was generated by the dual virus strategy but foot shock application preceded photostimulation.

C. The percentage of time naïve ChR2-expressing animals spent in each chamber during a 5 minute (N=2) or 10 minute (N=8) testing period. One of the side chambers in a three-chambered arena was chosen as the (+) photostimulated compartment. Photostimulation was applied only when the animals entered the (+) photostimulated chamber. Training was not involved. ChR2 was densely expressed using the dual virus strategy.

D. The percentage of trials in which ChR2-expressing animals (N=3) exhibited flight behavior in response to a complete multi-component CS or its components after training in the aversive conditioning paradigm. The complete CS was an odorant mix (ethyl acetate + citronellol) co-delivered with photostimulation. Odorant component was either ethyl acetate or citronellol. ChR2 was densely expressed using the dual virus strategy.