Frequency and synchrony of tetanically-induced, gamma-frequency population discharges in the rat hippocampal slice: the effect of diazepam and propofol.
Fox JE., Jefferys JG.
Fast, rhythmic discharges, at gamma frequencies, have been evoked in the CA1 region of the hippocampus by tetanic stimulation applied via pairs of electrodes placed close to the pyramidal layer. The discharges had a latency of 65-225 ms and a frequency of 60-100 Hz; they were synchronous (phase lag < 2 ms) when recorded from sites 0.4-0.8 mm apart. Diazepam (5-15 microM) and propofol (5 microM) reduced the frequency by 15-26%, but had no significant effect on synchrony or phase lag, suggesting that the generation and synchrony of this rhythm are pharmacologically distinct. 10 microM propofol had a more marked effect and, when frequency fell by approximately 50%, synchrony was also reduced.