High-frequency and medium-frequency components of different inspiratory nerve discharges and their modification by various inputs.

In decerebrate paralyzed cats, spectral analysis was performed on simultaneous recordings of efferent inspiratory nerves (phrenic, recurrent laryngeal, hypoglossal). Spectral peaks were present both in the high-frequency (HFO) range (50-100 Hz) and the medium-frequency (MFO) range (20-50 Hz). Different activities were coherent only in the HFO range, indicating that the HFOs arise in a common inspiratory pattern generator that drives the different motoneuron populations, whereas the MFOs are specific to different systems.