DISCHARGE PATTERNS OF BOTZINGER COMPLEX NEURONS DURING COUGH IN THE CAT

This study was carried out on pentobarbital sodium-anesthetized, spont aneously breathing cats to address the hypothesis that Botzinger compl ex (BotC) neurons are involved in the production of the cough motor pa ttern 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 Bo tC neurons (n = 87) were performed. The majority of augmenting expirat ory (E-Aug) neurons encountered (n = 47) displayed excitatory response s during the expulsive phases of coughing in parallel with the main co mponents of the abdominal bursts and the corresponding increases in tr acheal pressure. We also encountered E-Aug neurons markedly depressed up to complete inhibition during coughing (n = 14) as well as E-Aug ne urons 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 excit atory responses, whereas others were depressed (n = 3) or completely i nhibited (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 t o caudal expiratory neurons and, hence, to expiratory motoneurons.