Figure 1.

Schematic showing the experimental layout for measuring CO₂-evoked behavior and conditioned responses to context exposure. Following arrival animals were acclimated to the facility for a week prior to behavioral measurement. The CO₂ inhalation paradigm (Day 1–3) consisted of habituation (Day 1) where animals were exposed to the CO₂ chamber for 10 minutes. On Day 2, animals were exposed to either air or CO₂ (10%) for 10 minutes while being videotaped. 24hr post inhalation animals were returned to the CO₂ context for 5 minutes in the absence of gas inhalation and were videotaped. Following behavior, animals were sacrificed and brain tissue collected for further analyses.