Figure 1.
resolution MR images of the mouse lemur brain at 7T.
1: corpus callosum; 2: caudate nucleus; 3: septal nuclei; 4: thalamic medullary stria; 5: fornix; 6: lenticular nucleus; 7: optic chiasm; 8: hippocampal fimbria; 9: thalamus; 10: external medullary lamina; 11: Forel's field; 12: mamillo-thalamic tract; 13: cerebral peduncle; 14: optic tract; 15: hippocampus; 16: lateral geniculate body; 17: median lemniscus; 18: posterior commissure; 19: central grey matter; 20: substantia nigra; 21: medial geniculate nucleus; 22: central interpedoncular nucleus; 23: dentate gyrus. Based on [32].
Figure 2.
Analysis of hippocampal subfield volumes.
(A) Segmentation of the hippocampus, divided into the dentate gyrus and the extended Ammon's horn (includes CA1, CA2, CA3, CA4 and subiculum), based on the mouse lemur brain atlas [48]. No correlation was found between age and total hippocampal volume (B), however, we observed a significant decrease with age of the normalized volume of the extended Ammon's horn (C), and a significant increase with age of the normalized volume of the dentate gyrus (D). (E–F) 3D views of hippocampal subfields in one young (E) and one old animal (F), showing the increased volume of the dentate gyrus and decreased volume of the Ammon's horn in the aged lemur as compared to the young one.
Figure 3.
Detection of cortical and hippocampal black dots.
(A) Example of the black dots detected in the cortex of mouse lemurs on MR images. (B) The number of black dots in each animal was significantly correlated with age (p<0.005). In one animal, some black dots visible on MR images (C) matched the location of amyloid deposits detected by Abeta staining (D, 4G8 staining, white circles). The level of iron within amyloid deposits was similar or slightly higher than in the surrounding parenchyma (E, Perls-DAB staining). In animals without amyloid deposition, the location of black spots on MR images (F, arrows) corresponded to focal area of microhemorrhages detected by Perls staining (G, arrows).