Figure 1.

Loss of SynCAM 1 affects connectivity in select brain regions. A, Left, diagram from the Paxinos atlas (Paxinos and Franklin, 2001) for anatomic overlay. Center, Average FA map of a composite coronal slice from WT mouse littermate control brains at P28. Right, SynCAM 1 KO brains. Yellow ellipsoids mark hippocampal CA3 areas with reduced FA in KO brains. B, 3D rendering of regions with significant FA differences of WT and SynCAM 1 KO littermates (n = 6 male mice each). Bilateral FA reduction was measured in the hippocampal CA3/CA2 areas (yellow; KO 78 ± 7% of WT, p < 0.00004, two-tailed t test) and lateral posterior hippocampus (LPH, brown; KO 78 ± 7%, p < 0.00028). FA was increased in retrosplenial granular cortex/presubiculum/upper CA1 (RSG/PRS/uCA1, red; KO 130 ± 14%, p < 0.00004), parts of somatosensory cortex (S1, light blue; KO 125 ± 10% p < 0.00009), subcortical intercollicular nucleus/deep gray layer of superior colliculus/intermediate white and gray layers of superior colliculus (ICN/dgSC/iSC, dark red; KO 124 ± 12%, p < 0.0002), and lower cingulum and central corpus callosum (lCG/cCC, light green; KO 134 ± 19%, p < 0.0014). The lateral globus pallidus (LGP) was the only region with unilateral FA changes (left hemisphere, blue; KO 120 ± 11% p < 0.0002). See Table 1 for regional differences. C, Bilateral FA reduction in the CA3 area of KO compared with WT (KO 76 ± 5% p = 0.023, n = 6 male mice each group). D, Left, Coronal section immunostained at P28 for SynCAM 1 with hippocampal areas marked. Right, Strong SynCAM 1 staining in CA3 stratum lucidum (sl). pcl, Pyramidal cell layer; so, stratum oriens; sr, stratum radiatum. Scale bars: overview, 1 mm; inset, 100 μm.