Discharge patterns of Botzinger complex neurons during cough in the cat

This study was carried out on pentobarbital sodium-anesthetized, spontaneously breathing cats to address the hypothesis that Botzinger complex (BotC) neurons are involved in the production of the cough motor pattern induced by mechanical stimulation of the tracheobronchial tree. Phrenic nerve and abdominal muscle activities as well as intratracheal pressure were monitored; single-unit extracellular recordings from BotC neurons (n = 87) were performed. The majority of augmenting expiratory (E-Aug) neurons encountered (n = 47) displayed excitatory responses during the expulsive phases of coughing in parallel with the main components of the abdominal bursts and the corresponding increases in tracheal pressure. We also encountered E-Aug neurons markedly depressed up to complete inhibition during coughing (n = 14) as well as E-Aug neurons assuming a decremental pattern without any increase or even with some reduction in their peak activity (n = 15). During the expiratory thrusts, most decrementing expiratory neurons (n = 7) presented excitatory responses, whereas others were depressed (n = 3) or completely inhibited (n = 1). The results are consistent with the view that these neurons are involved in the generation of the cough motor pattern and, in particular, that some BotC E-Aug neurons convey excitatory drive to caudal expiratory neurons and, hence, to expiratory motoneurons.