Figure 1. Developmental strengthening of the VCN-LSO pathway is enhanced in Fmr1 KO mice. Sample input–output curves in WT (A, in black here and throughout) and Fmr1 KO mice (B, in red here and throughout) reveal an impaired development of the VCN-LSO connections in Fmr1 KO mice at the end of the third postnatal week. A, Inset, Schematic of the performed experiment. Summary data show evoked EPSC (eEPSC) amplitudes in response to maximal (C) and minimal (D) stimulation of the ipsilateral, excitatory fibers in the developing LSO. E–I, Confocal images display an enrichment of FMRP over development of the LSO neurons. E, F, Validation of the antibody against FMRP in sections including LSO. Dashed squares indicate where the high-power images were taken. G–I, Somata and proximal processes (white arrows) of LSO neurons are strongly FMRP-immunoreactive between P8 and P21. Blue represents DAPI staining. Magenta represents FMRP staining. Green represents MAP2 staining. Scale bars: E, F, 100 μm; E′, F′, 50 μm; G, H, I, 20 μm. Bar graphs represent mean ± SEM. p < 0.05 was considered statistically significant. *p < 0.05 (two-way ANOVA followed by Bonferroni post tests). **p < 0.01 (two-way ANOVA followed by Bonferroni post tests).