Fig. 4: Stimulation of the median raphe nucleus inhibits prefrontal pyramidal neurons through the act i va tion of 5-HT1A receptors. In the upper panel, a peristimulus-time histogram shows the presence of an inhibition (latency 32 ms, duration 100 ms) evoked by the electrical stimulation of the median raphe nucleus (0.9 Hz, 0.2-ms square pulses, 2 mA). The lower panel shows the blockade of the inhibition by intravenous administration of the selective 5-HT1A receptor antagonist WAY-100635 (40 μg/kg). Bin size 4 ms, 180 sweeps.