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. 2014 Jan 22;34(4):1258–1270. doi: 10.1523/JNEUROSCI.3865-13.2014

Figure 7.

Figure 7.

Sensory-experience-dependent somatotopic refinement via synapse elimination. A, Experimental schedule and schematic view of whisker deprivation. B, Acute slice patch-clamp recordings from Krox20-Ai14 mice. Clouds of tdT-positive terminals were observed in the dorsal part of the VPM via a confocal laser scanning unit and the whole-cell recordings were then made from thalamic neurons under the infrared-differential interference contrast (IR-DIC) viewing. After the recordings, slices were fixed and we confirmed that the recorded thalamic neurons had been in the clouds of tdTomato-positive lemniscal fiber terminals. The arrow indicates the recorded thalamic neuron. Scale bars, 200 μm. ml, Medial lemniscus; Rt, reticular nucleus of thalamus. C, Representative traces of lemniscal EPSCs from intact and deprived mice under voltage-clamp conditions at +40 and −70 mV. Several raw traces with different stimulus intensities are superimposed at each holding potential. EPSCs from an intact mouse showed all-or-none responses, whereas those from a deprived mouse showed stepwise increments in amplitude. D, Distributions of neurons with different numbers of steps of lemniscal EPSCs. n = 46 and 47 neurons of seven and nine mice for intact and deprived groups, respectively. E, VGluT2-immunostained whisker-sensory thalamic sections of intact and deprived Krox20-Ai14 mice. Scale bars, 20 and 5 μm for left and right, respectively. F, G, Density and size of tdT(+)- and tdT(−)-VGluT2 puncta of intact and deprived Krox20-Ai14 mice. Forty images from 7–8 mice were analyzed for each group. H, Proportion of tdT-positive puncta plotted against EPSC steps. Whisker deprivation at P12–P13 consistently disrupted synapse elimination and somatotopic refinement. r, Pearson's correlation coefficient. The broken line is the regression line. Values are represented as mean ± SD. Statistical significance was tested by Kolmogorov–Smirnov two-sample test for D and Student's t test for F and G. *p < 0.05; **p < 0.01; n.s., not significant, two-tailed test.