Figure 7.
Presynaptic modulation of ON input via GABAB receptors is present and mature in the first postnatal week. A, Example traces recorded from PGCs at P5 and P26, showing AMPA responses to paired-pulse stimulation (50 ms ISI, −70 mV). Control traces (gray) show strongly depressing responses before the addition of the GABAB receptor agonist baclofen (0.5 μm). Black traces show responses after baclofen application: initial response amplitude is decreased and PPR becomes less strong, consistent with a decrease in presynaptic release probability. B, Group comparisons show that baclofen's effects on initial response amplitude and PPR are significant in both the first (W1) and the fourth (W4) postnatal weeks (1-sample t test vs 1; *p < 0.05; **p < 0.01; ***p < 0.001), but do not differ significantly between different stages of ON input maturation.