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. 1996 Dec 1;16(23):7566–7573. doi: 10.1523/JNEUROSCI.16-23-07566.1996

Fig. 4.

Fig. 4.

Both serotonin and baclofen enhance the paired-pulse IPSC ratio. A, Superimposed records from two different cells showing the effects of serotonin (3 μm; left) and baclofen (3 μm; right), relative to control in each case, on successive IPSCs evoked with the same stimulus at an interpulse interval of 50 msec. In control conditions, paired-pulse facilitation was observed in which the second IPSC was larger than the first. Both serotonin and baclofen reduced IPSC amplitude, but the second IPSC of the pair was reduced to a lesser extent than the first. Shown are IPSCs preceded by current resulting from +5 mV test step. Holding potential is −50 mV. Ritanserin (3 μm), CNQX (10 μm), and d-AP5 (50 μm) were present throughout. B, Same data as in A, but records in the presence of serotonin and baclofen are rescaled digitally so that the first IPSC of the pair is of similar amplitude to control. The second IPSC is clearly larger relative to control in the presence of both serotonin and baclofen, indicating that the depression of the IPSC (in A) by serotonin and baclofen occurs at a presynaptic locus.