Discharge identity of dorsolateral pontine single units in the expiratory class. Recordings from central vagus nerve (cVN, blue), phrenic nerve (PN, pink), and dorsolateral pontine units [raw data shown in gray (Extracell), sorted units shown in black (Unit)] were made using an in situ preparation of rat. Units were placed into subgroups depending on their pattern of activity over the respiratory cycle (A–E). Left column: example traces of a recorded unit with corresponding nerve output for each subgroup. Right column (histograms): average firing frequency per phase fraction bin for 10 consecutive breaths was plotted for individual units in each group. Each unit was assigned a number, which is indicated to the right of the histogram and is used consistently throughout the Figures. Inspiration (Insp) is indicated by gray shading. Expiration was duplicated to display phase transitions.