Patterns of respiratory neuronal discharge in the pre-Bötzinger complex, hypothesized as a brainstem site generating respiratory rhythm, are described in adult cats. Signals were recorded from neurons in the Bötzinger complex, pre-Bötzinger complex and rostral ventral respiratory group (rVRG) of anesthetized adult cats. The pre-Bötzinger complex, located caudal to expiratory-modulated Bötzinger neurons, contained a mix of neurons with inspiratory-modulated, expiratory-modulated, or phase-spanning patterns of impulse activity, in contrast to the more homogenous neuronal distributions characteristic of adjacent Bötzinger and rVRG regions.