Fig. 4. Effects of isoflurane on spontaneous inhibitory postsynaptic currents. (  A ) Two epochs comprising 10 s of continuous spontaneous activity recorded under control conditions (  left ) and in the presence of isoflurane (0.1 mm  ;  right ). The small change in holding current observed in this cell was typically also observed in the absence of drug application. (  B and  C ) Averaged and normalized spontaneous inhibitory postsynaptic currents recorded in 0.1 mm isoflurane (  B ; same cell as in  A ) and 0.5 mm isoflurane (  C ). Ctrl = control; Iso = isoflurane.