Fig. 2.

Criteria for identifying pacemakers.A, In 8 mm[K⁺]_o aCSF, inspiratory pacemaker bursts are in phase with ∫PBC bursts. B, Bath application of CNQX, CPP, bicuculline, and strychnine eliminates ∫PBC bursts while pacemaker neurons continue bursting. Brief current injection reset the ongoing rhythm, the timing of which is demarcated by black bars above the neuron recording. C, Injecting depolarizing current into synaptically isolated pacemakers increased the bursting frequency (top neural trace), whereas hyperpolarizing current terminated bursting during current injection (bottom trace). The y-axis scale in A applies toB and C.