Thiopental did not affect fEPSPs. A-B. Evoked fEPSPs from CA1 st. radiatum (upper traces, averages of ten sweeps) and continuous records of SPW-Rs from CA1 st. pyramidale (lower traces) obtained in normal medium (left panels) and in medium containing 50 or 100 μM of thiopental (right panels). fEPSPs and spontaneous activity were simultaneously recorded from two neighboring slices in "A" and from the same slice in "B". Note that the drug did not affect fEPSPs despite its suppressive effect on spontaneous activity. C-D. Grouped data of fEPSP slope for the two concentrations of thiopental. The drug did not significantly change the slope of fEPSP at any concentration.