A typical example of propofol-induced spike synchrony between two pyramidal neurons. (A) Schematic of triple whole cell patch clamp recording from a fast-spiking neuron and two pyramidal neurons. (B) Representative unitary inhibitory postsynaptic currents obtained from postsynaptic pyramidal neurons (pyramidal neuron 1 and pyramidal neuron 2) responding to an injection of five train pulses to the presynaptic fast-spiking neuron (20 Hz) in a single-slice preparation. In these connections, pyramidal neuron 1 receives larger inhibitory inputs than pyramidal neuron 2. Ten consecutive traces are superimposed. The holding potential was set at −45 mV. (C and D) Pyramidal neuron spike recordings in the control (C) and during propofol (10 μM) application (D). Four short voltage pulses (pulse duration = 1 ms, 80-mV voltage step) were applied to the fast-spiking neuron at 10 Hz. Ten consecutive traces are superimposed. Note that a bath application of propofol reduced the difference in spike timing in pyramidal neuron 1 and pyramidal neuron 2 just after fast-spiking neuron activation (arrows). The calibration of the traces of the membrane potential of pyramidal neuron 1 (top, 20 mV; bottom, −40 mV) is applied to the other membrane potential traces in (C and D). (E and F) Spike recordings of pyramidal neurons 1 and 2 before (E) and during the 10 μM propofol application (F). Four bursts that each consisted of five train pulses at 100 Hz were applied to the fast-spiking neuron at 6.7 Hz. Note that bath application of propofol reduced the difference in spike timing in pyramidal neuron 1 and pyramidal neuron 2 just after fast-spiking neuron activation (arrows).