Figure 1. Relief of baclofen-mediated inhibition during paired-pulse stimulation causes frequency-dependent facilitation in retinohypothamic tract synapses.

A–C, paired-pulse stimulation of the optic chiasm. A, paired-pulse ratio plotted against stimulus frequency (control, baclofen 10 μm, n= 8). The paired-pulse ratio equals the mean eEPSC₂/mean eEPSC₁, where the eEPSC₁ and eEPSC₂ are the first and the second eEPSC in the pair of stimuli, respectively. Short-term synaptic depression was observed in control, while frequency-dependent facilitation was observed during baclofen application. B and C, eEPSC recordings made from the same neuron in control (C) and during baclofen application (B); 50 Hz paired-pulse stimulation, arrows – stimuli application. *P ≤ 0.05, **P ≤ 0.01 (paired t test, two-way). eEPSC, evoked excitatory postsynaptic current.