Reduced barreloid segregation in Syngap^−/− mice. Cytochrome oxidase staining in VpM of thalamus to reveal barreloids in Syngap^+/+ (a, d), Syngap^+/− (b, e), and Syngap^−/− (c, f) mice at P4 (a–c) and P7 (d–f). Barreloids can be clearly seen in all genotypes at both P3/4 and P7; however, segregation is clearly reduced in Syngap^−/− mice (n = 5) at both ages relative to Syngap^+/+ (n = 8) and Syngap^+/− (n = 12) mice, especially in the anterior snout representations. Coronal section through the brainstem trigeminal complex stained for cytochrome oxidase in P3/4 control (g, i; n = 10) and Syngap^−/− (h, j; n = 6) mice showing normal barrelette formation in PrV (g, h) and SpI (i, j). Scale bars: (in f) a–f, 350 μm; (in j) g, h, 225 μm; (in j) i, j, 250 μm.