Functional interactions between cough modulated raphe and ventral respiratory column (VRC) neurons.

The respiratory pattern generation network in the ventrolateral medulla undergoes reorganization to produce coughing. We are currently in the process of identifying populations of neurons that may regulate the discharge of VRC neurons during cough. We have recently shown that neurons in the raphe nuclei undergo alterations in discharge during coughing. We speculated that these neurons would functionally interact with VRC neurons that also were cough‐modulated. Data were obtained from eight decerebrated paralyzed cats. Fictive cough was elicited by mechanical stimulation of the trachea or larynx. Electrode arrays were used to record extracellular potentials from raphe and VRC neurons during fictive breathing and coughing. In most cases, raphe neurons had little respiratory modulation of their discharge during fictive breathing but were recruited or strongly modulated during fictive coughing. Cross correlation analysis revealed evidence consistent with shared excitation between raphe and VRC neurons, excitation of raphe neurons by VRC cells, and inhibitory and excitatory effects of raphe neurons on VRC cells. The results further support the participation of raphe neurons in the brainstem network responsible for cough. Moreover, these results support an important role for non‐respiratory modulated neurons within the raphe nuclei in this network. Supported by NIH HL70125, HL 49813, and NS 019814.