Table 2.

Ipsilateral retinal input and size of the SC in medial and lateral slices

Property	Medial Slice (n = 12)	Lateral Slice (n = 9)	Relative Difference (medial vs. lateral slices)	P Value
Area of ipsilateral retinal input in 0.2–0.6 portion of SC along rostro-caudal axis, mm2	0.22 ± 0.06	0.08 ± 0.03	175%	0.0013
Max. brightness of ipsilateral retinal input in 0.2–0.6 portion of SC along rostro-caudal axis	0.13 ± 0.06	0.03 ± 0.02	333%	0.009
Length of SC at P7, mm	2.70 ± 0.11	2.48 ± 0.24	9%	0.39
Width of SGS, mm	0.36 ± 0.02	0.33 ± 0.03	9%	0.35

Data are presented as means ± SE. To quantify the amount of ipsilateral input in the medial and lateral slices, we divided the SC into 5 segments along the antero-posterior axis (Fig. 1D). All electrophysiological recordings were preformed in the 0.2–0.6 portion of the SC along the antero-posterior axis, that is, segments 2 and 3 (Fig. 1F). In these segments, the ipsilateral input was dramatically more prominent in the medial vs. the lateral slice: it covered a larger area and its intensity was higher (rows 1 and 2, 2-tailed Student's t-test). The difference in the area of the ipsilateral projection between the 2 slices cannot be accounted for by a difference in size of the SC itself. Even though the length and width of the SGS, as measured through labeling of the contralateral projection, were slightly (9%) smaller in the lateral compared to the medial slice, these differences were not statistically significant and can account for only a small fraction of the larger area of the ipsilateral projection in the medial slice. Ipsilateral enucleation at P0 did not affect the size of the SC (P > 0.05). Retinal input brightness values are in arbitrary units.