Synaptic inputs to preBötC neurons. A. Spontaneous postsynaptic currents from an inspiratory neuron voltage clamped at -60 mV. Note both iPSCs from ePSCs appear as inward currents. B. The same neuron as in A, but voltage clamped at -35 mV. Note that chloride-mediated synaptic currents now appear as outward currents (arrows). Although it is impossible to accurately measure the amplitude or frequency of excitatory or inhibitory inputs during inspiration-related bursts of synaptic input it is possible to distinguish between excitatory and inhibitory inputs during the interburst interval. Vertical scale: 50 pA.