Intracellular recordings from upper cervical inspiratory neurons in the cat

Intracellular recordings were made from propriospinal, inspiratory neurons, at the lateral edge of lamina VII in the upper cervical cord of the cat. The membrane potentials were found to fluctuate with the central respiratory rhythm, as determined from a recording of the phrenic nerve discharge. Excitatory postsynaptic potentials occurred during the inspiratory phase, and inhibitory postsynaptic potentials were shown to occur in the expiratory phase by injecting chloride to reverse them. These recordings are the first demonstration that the upper cervical inspiratory neurons receive both excitation during inspiration and inhibition during expiration.