Fig. 3. Effects of various concentrations of propofol on long-term potentiation. Propofol was dissolved in dimethyl sulfoxide (DMSO) and continuously administered for the duration shown by the solid bars . One hundred–hertz θ-burst stimulation (TBS) was delivered at time 0 ( arrow ). TBS induced long-term potentiation when 0.1% DMSO alone was administered ( A ) or when 3 μm propofol was administered ( B ). Administration of 10 μm propofol significantly depressed long-term potentiation production ( C ), whereas 30 μm propofol completely blocked long-term potentiation ( D ). Traces to the right of the graphs depict representative excitatory postsynaptic potentials (EPSPs) obtained before ( dashed traces ) and 60 min after TBS ( solid traces ). EPSPs were obtained from slices treated with DMSO alone ( upper traces ), 3 μm propofol ( second set of traces ), 10 μm propofol ( third traces ), and 30 μm propofol ( bottom traces ). Scale bar : 2 mV, 5 ms .