The sneeze: maturation of the reflex in kittens.

This is the first study to compare the influence of nasal afferent stimulation on inspiratory and expiratory muscle activity during sneezing, in kittens and adult cats. In kittens, we demonstrate that nasal afferent stimulation does not reinforce inspiratory activity prior to the expiratory thrust as it normally does in adult cats. These stimulations evoke an active expiration similar to but weaker than the expiratory thrusts observed under the same conditions during sneezing in adult cats. Sneezing can be elicited from three weeks of life. Among the different hypotheses discussed, the most likely explanation appears to be the immaturity of medullary respiratory connections.