The activity of retrofacial expiratory cells during behavioral respiratory responses and active expiration

The activity of retrofacial expiratory cells was recorded from cats trained to inhibit inspiration in response to a tone. Because retrofacial expiratory cells inhibit inspiratory cells, we thought they might mediate this response. We found, however, that these cells were inactive during the response and thus could not be the mediators thereof. Moreover, retrofacial expiratory cells were inactive also during sneezing and thus were not acting as expiratory upper motoneurons during these active expirations. We propose that they act to promote and synchronize inspiratory activity.