This figure, taken from our recent study (Luo et al., 2007), shows that microinjection of glycine or muscimol into the preBotzinger complex causes transient apnea. Panel A shows representative recordings from saline-exposed and nicotine-exposed neonates, and demonstrates that the duration of the transient, drug-induced apnea is longer in the nicotine-exposed animals. Panel B provides average values for apnea duration induced with either drug, in saline-exposed and nicotine-exposed neonates. As discussed in the text, these effects of drug injection must be due to actions on GABAA receptors located on the post-synaptic membrane of neurons that control respiratory motor output.