Fig. 4. Isoflurane blocks the induction of long-term potentiation. Summary of nine experiments. Field excitatory postsynaptic potentials (fEPSPs) were evoked by two independent inputs, positioned in the same slice. Long-term potentiation without isoflurane: input 1 (left ). Long-term potentiation in isoflurane: input 2 (right ). The arrow indicates the time of tetanic stimulation. Data points have been calculated as in figure 3.