CEREBELLAR MODULATION OF COUGH MOTOR PATTERN IN CATS

The cerebellum modulates respiratory muscle activity in part via its i nfluence on the central respiratory pattern generator. Because coughin g requires well-coordinated respiratory muscle activity, studies were conducted to determine whether the cerebellum influences the centrally generated cough motor pattern. Integrated phrenic and lumbar efferent neurograms (integral PN and integral LN, respectively) were monitored in decerebrated, paralyzed, and ventilated cats. Mechanical probing o f the intrathoracic trachea was used to evoke fictive coughs; i.e., la rge increases in integral PN and integral LN amplitudes. Cerebellectom y resulted in a decrease in the number of coughs per trial (cough freq uency) and integral LN peak amplitudes without any consistent change i n integral PN peak amplitudes. Cerebellar nuclei [the rostral interpos ed nucleus (INr) and the rostral fastigial nucleus (FNr)] known to be involved in respiratory control were ablated to determine their potent ial role in the cough response. Control (eupneic) respiratory frequenc y was not affected by cerebellectomy or INr/FNr lesions. Cough frequen cy was depressed by lesion of the INr but not by ablation of the FNr. No significant changes in integral PN and integral LN amplitudes were observed after lesion of either the INr or FNr. These results suggest that the cerebellum, specifically the INr, is involved in modulation o f the frequency of centrally generated coughing.