BNST lesions reduce CO2-evoked behavior. A, Diagram representing location and size of the largest (gray) and smallest (black) lesions (Paxinos and Franklin, 2001). B, BNST lesions reduced CO2-evoked freezing. C, BNST lesions significantly reduced conditioned avoidance to CO2. D, BNST lesions did not alter minute ventilation (VE). E, BNST lesions did not alter locomotion in the open field.