Onset and control of expiratory laryngeal discharge: cross-correlation analysis

In anaesthetized, paralysed and artificially ventilated cats, spontaneous activity of pairs of expiratory laryngeal motoneurones was recorded and submitted on line to cross-correlation analysis in order to reveal the underlying mechanisms which govern their discharge. In 45/52 pairs, flat cross-correlograms were obtained suggesting independency between the expiratory laryngeal motoneurones. Synchronization by common central respiratory drive was never observed. This negative result is in agreement with the post-inhibitory rebound hypothesis put forward to explain the discharge of expiratory laryngeal motoneurones. In 7/52 pairs, cross-correlation revealed a bell-shaped increase of probability of firing which is relevant with broad synchronization of the discharges by common peripheral afferents.