Figure 5.

Central respiratory pattern of RTN neurons. The patterns were classified according to the number and timing of the periods of reduced discharge probability relative to PND. The nomenclature reflects the assumption that the maximum discharge rate (apex of the histogram) is primarily defined by the intrinsic response of the cell to pH and that changes in firing probability down from this maximum are caused by inhibitory inputs. The early-I/post-I pattern was dominant, and several variants are shown. The pattern change caused by elevating CO₂ is shown for cells 48-4 and 48-5. Histogram G12-4 is shown at a higher time resolution. This pattern is interpreted as a series of inhibitions that occur during the early-I, post-I, and E2 phases, i.e., throughout except during late inspiration. The X at the top right corner of some of the histograms identifies the rat as vagotomized. Patterns 2a and 2b differ according to whether inspiratory inhibition is decrementing (2a) or incrementing (2b). Note that the nadir can occur in early-I, post-I, or late-expiration (E2) depending on the cell.