Fig. 5. The effects of halothane and isoflurane on (A ) first fEPSP amplitudes and (B ) second fEPSP responses are summarized. An interstimulus interval (60 ms) was used to obtain paired pulse facilitation. The effects of isoflurane on NMDA fEPSPs were significantly greater than for those of halothane or isoflurane on non-NMDA responses (n = 7 for halothane on non-NMDA fEPSPs, n = 5 for the other three responses, mean ± SD, P < 0.001, ANOVA).