Figure 4. Enrichment from birth leads to a loss of ipsilateral retinal inputs to ventral dLGN in Ten-m3 KOs. Graphs show quantification of total ipsilateral inputs and their relative distribution in the dLGN. Data derived from individual animals in each group is shown. Thick black lines show group means, boxes indicate s.e.m.. Housing groups are separated by age with the birth cohort shown on the left, weaning groups in the middle, and adults on the right. The same shading and color coding for housing; lighter shade for standard-housing groups (SE), darker for all EE groups, and genotype (blue for WT; red for KO) is used across age groups for ease of comparison. All SE WTs are shown in light blue and all EE WTs are shown in darker blue. All SE KOs are shown in orange, and all EE KOs are shown in red. A, Percentage of total dLGN occupied by ipsilateral terminals. A slight but significant decrease was seen between the SE-B WTs versus the EE-B WTs (gray ***p < 0.001). A decrease of greater magnitude was detected between SE-B KOs and EE-B KOs (black ***p < 0.001), consistent with the decreased expanse of ipsilateral terminals observed qualitatively in the enriched from birth cohort. A small but significant decrease was also observed between the SE-B WTs and SE-A WTs (gray **p = 0.003), suggesting that pruning of retinogeniculate terminals continues well after adolescence in standard-housed WTs. EE-B KO values were significantly smaller than EE-W KOs (*p = 0.021) and EE-A KOs (*p = 0.023), indicating that the timing of enrichment had a major impact on pruning of ipsilateral projections. No effects of housing or genotype on total ipsilateral area were seen within the weaning or adult groups. B–D, Relative distributions of ipsilateral terminals across the dorsal (D), middle (M), and ventral (V) thirds of the dLGN for birth (B), weaning (C), and adult (D) SE and EE cohorts (see Materials and Methods). Stacked bars show mean values (large single-color boxes) plus s.e.m. (smaller flanking boxes of the same color, present on both top and bottom of each mean box) for proportion of ipsilateral terminals present in D, M, and V regions. Within WTs, there was no detectable change in distribution across regions of ipsilateral terminals between ages or housing conditions. No terminals were found in the ventral third of the dLGN in WTs. SE-B KOs had significantly less label in dorsal dLGN (▿▿▿p < 0.001) and significantly more label in ventral dLGN (▴▴▴p < 0.001) than SE-B WTs. In EE-B KOs, there was a significant increase in the percentage of terminals in the dorsal region (▿▿▿p < 0.001) along with a significant decrease in the ventral region (▴▴▴p < 0.001), compared to SE-B KOs. No difference in the proportion of ipsilateral terminals in dorsal (p = 0.158) as well as ventral (p = 0.112) dLGN was observed between EE-B KOs and EE-B WTs. A detectable decrease in EE-B KOs relative to EE-B WTs was also present for the middle region (⧫⧫p = 0.003). Weaning and adult groups showed differences in the ventral region with respect to genotype but not housing (KOs > WTs: p < 0.001 in C, D).