Fig. 5. Isoflurane increases the latency and variability of solitary tract–evoked excitatory postsynaptic currents (EPSCs). Raw current traces of EPSCs from one neuron under control conditions (  black ,  A1 ) and in the presence of isoflurane (  gray ,  A2 ). Solitary tract–evoked EPSCs were measured every 3 s. Isoflurane (ISO) produced an increased latency between the solitary tract shock and EPSC onset in 6 of 10 neurons tested (  A2 ). The average change in latency was 550 ± 60 μs (n = 6 neurons). In half (5 of 10) of the neurons tested at the highest concentrations (>300 μm), at least one complete EPSC failure was also observed (  gray ,  A3 ). (  B ) A corresponding frequency histogram showing the change in latency distribution under control conditions (  black ) and in the presence of isoflurane (  gray ) as represented in  A .