Figure 2.
AMPAR-mediated synaptic transmission is diminished and inward rectification enhanced at stargazer PF-SC synapses without an effect on paired-pulse ratio. A, Overlay of AMPAR- and NMDAR-mediated eEPSCs from a wild-type (left) and a stargazer (right) SC. The bottom traces were recorded at a holding potential of −60 mV in the presence of picrotoxin. The top traces were at a holding potential of +40 mV in the presence of NBQX and picrotoxin. Stimulus artifacts were removed for clarity. B, Bar plot showing values for AMPA/NMDA ratios (peak IAMPA/peak INMDA). Stargazer (stg) SCs exhibit AMPA/NMDA ratios that are reduced by 69.7% relative to wild-type (wt) SCs (wt: average AMPA/NMDA ratio = 10.7 ± 1.7, n = 12; stg: average AMPA/NMDA ratio = 3.3 ± 0.5, n = 11; p < 0.0001, Wilcoxon rank sum test). C, Representative paired-pulse traces (interstimulus interval = 20 ms) for a wild-type (left) and a stargazer (right) SC at a holding potential of −60 mV. Stimulus artifacts are removed for clarity. D, Bar plot of paired-pulse ratio (EPSC2/EPSC1) represented as mean ± SEM, showing no significant difference between wild type and stargazer (wt: average PPF = 1.78 ± 0.09, n = 12; stg: average PPF = 1.77 ± 0.1, n = 9, N.S.). E, Overlay of eEPSCs in a wild-type (left) and stargazer (right) SC measured at −60, 0, and +40 mV in the presence of picrotoxin and D-AP5, with stimulus artifacts blanked. Insets show normalized I–Vs for each example. F, Bar graph showing collected RI values for wild-type and stargazer mice (wt: average RI = 0.46 ± 0.02 pA, n = 75; stg: average RI = 0.23 ± 0.02 pA, n = 43; p < 0.0001, Wilcoxon rank sum test). Open circles represent values from individual cells. Asterisks indicate significance: ***p < 0.0005, N.S. is not significant.