Figure 1.

Topographic mapping of the retinocollicular projection in wild-type mice and mice with increased EphA3. S = 2500; a = 1/80; and R_E = 36. C, R, Caudal and rostral superior colliculus (SC), respectively; N, T, nasal and temporal retina, respectively. A, Eph receptor density of the normal retinal ganglion cells (EphA3^-; thick line R(x_R) = S^1/2 exp[a (x_R - 50)]) and the retinal ganglion cells with increased EphA3 receptor (EphA3⁺; broken line; R(x_R) = S^1/2 exp[a (x_R - 50)] + R_E) on the retina. B, Ligand ephrin density in the SC. L(x_L) = S^1/2 exp[a (x_L - 50)]. C, Topographic maps of the elevated retinal ganglion cells EphA3⁺ (a) and normal retinal ganglion cells EphA3^- (b). x_R (percent nasotemporal axis of retina) is the starting point of axonal projection, and x_L (percent rostrocaudal axis of the SC) is the arrival point. Topographic map of the retinal ganglion cells (b) is on the line x_R + x_L = 100. Solid circles, Actual data of the retinocollicular projection of wild-type mice by Brown et al. (2000); open circles, open triangles, actual data of the retinocollicular projection of knock-in mice with EphA3⁺ and EphA3^- retinal axons (Brown et al., 2000), respectively.