Article Figures & Data
Figures
- Figure 1.
Retinogeniculate excitation and feedforward disynaptic inhibition in dLGN brain slice recordings from D2-control and D2. A, Voltage-clamp recording of monosynaptic retinogeniculate EPSC (black, −70 mV) in response to optic tract stimulation in a brain slice from a D2-control mouse. The disynaptic IPSC was recorded at 0 mV (blue) and was entirely blocked by gabazine (SR95531, 20 µM, red). B, Group data of D2-control EPSC and IPSC amplitudes (28 cells from 9 mice). C, EPSC and IPSC recordings from a D2 mouse. D, Group data of EPSC and IPSC amplitudes from D2 brain slices (39 cells from 9 mice). E, F, Group data of EPSC and IPSC amplitudes. Nested t test performed on log-transformed data. **p < 0.01; *p < 0.05. G, Normalizing the IPSC to the EPSC amplitude shows a relative increase in the strength of feedforward inhibition in recordings from D2 brain slices. Nested t test performed on log-transformed data. *p < 0.05.
- Figure 2.
Measurements of quantal inhibitory currents in dLGN brain slices from D2 mice. A, Example traces of inhibitory synaptic currents measured in the absence of stimulation before (sIPSCs) and after (mIPSCs) application of 0.5 µM TTX. B, Example mIPSC waveforms from the example in A. C, Group data showing that TTX application led to a significant reduction in mIPSC amplitude (**p < 0.01, paired t test). D, Group data showing that TTX application led to a significant reduction in mIPSC frequency (p < 0.00001, paired t test). n = 13 cells. E, mIPSC recordings from D2-control and D2 mice obtained while voltage-clamping at 0 mV in the presence of 0.5 µM TTX, 20 µM CNQX, and 50 µM D-AP5. F, Noise-amplitude histograms show good separation of measured mIPSC amplitudes from recording noise for the examples shown. G, Group data of mIPSC frequency of recordings from D2-control (19 cells from 8 mice) and D2 (22 cells from 9 mice). Nested t test, ns p > 0.05. H, Example average waveforms of mIPSCs detected from the recordings in E. I, Group data of mIPSC amplitude, **p < 0.01, nested t test. J, The average mIPSC amplitude from all recorded cells for each mouse was linearly correlated with peak IOP.
- Figure 3.
Tests for inhibitory synaptic scaling. A, The plot of rank-ordered mIPSC amplitudes from D2 and D2-control recordings (1,900 mIPSCs from each group) fit using a linear regression model (solid line). Fit parameters had a slope of 1.45 and a y-intercept of −0.81. Dotted line, unity. B, Cumulative histograms of mIPSC amplitudes from recordings of D2-control (solid black line), D2 (solid red line), and D2 that were downscaled using the linear fit parameters from A. The downscaled mIPSC amplitude distribution significantly diverged from the D2-control distribution (p = 0.0071, K-S test). C, Rank-ordered mIPSC ratio plot shows that D2/D2-control ratios do not converge at a single scaling factor. D, Iterative scaling approach. K-S test p values from comparisons of the iteratively downscaled D2 distribution plotted against scaling factors. The scaling factor with the highest p value was 1.405, with p = 0.0031. E, Cumulative distributions of the D2-control mIPSC amplitudes and the D2 distribution downscaled by 1.405.
- Figure 4.
Peak-scaled nonstationary fluctuation analysis of mIPSCs. A, B, Example individual mIPSC events (gray traces) and mean event (black trace) from a D2-control recording (A) and D2 recording (B). Bottom, the mIPSC decay time constants were not significantly correlated with mIPSC amplitudes indicating adequate voltage clamp. C, Variance–mean plot from examples in A and B, showing parabolic fit parameters including single-channel current (i) and peak number of open receptors (N). D, Variance–mean plot of averaged (±SEM) variance and mean of mIPSC decay phases from D2-control recordings (15 cells from 6 mice) and D2 recordings (15 cells from 6 mice). Parameters of the parabolic fit are single-channel current (i) and peak number of open receptors (N). E, Single-channel conductance, measured by correcting for a 70 mV Cl− driving force, was not significantly different between D2-control and D2 (p > 0.05, nested t test). F, N was higher in D2 recordings compared with D2-control (*p < 0.05, nested t test).
- Figure 5.
Increased GABAA-α1 immunofluorescence in dLGN of D2 mice. A, Two-photon confocal images of GABAA-α1 staining. Images are average intensity projections of six optical sections (0.3 µm spacing). B, Quantification of average pixel intensity shows an elevated GABAA-α1 staining in dLGN of D2 mice (p < 0.01, t test).
- Figure 6.
vGAT labeling is similar in D2-control and D2 dLGN. A, Example two-photon confocal images (single optical sections) of vGAT labeling in dLGN. B, Quantification of detected vGAT punctum density (ns p > 0.05, t test; D2-control n = 13 mice; D2 n = 15 mice). C, Quantification of a detected vGAT punctum size (ns p > 0.05, t test).
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