Figure 1

Brain regions of study. A: Proton MR image of a coronal slice of rat brain obtained 1 week after kaolin injection into the cisterna magna. The lateral ventricles are enlarged and signal intensity in the white matter is increased due to edema. Representative regions of interest (ROIs) used for determination of MR parameters are shown in the dorsal cerebral cortex (DC), lateral cerebral cortex (LC), striatum (S), periventricular white matter (W), and ventricle (V). B and C: Schematic diagrams of rat brain showing regions sampled for water content and tissue density measurements. The dashed lines represent planes of dissection. The brain was cut in the coronal plane at the level of the optic chiasm approximately in the middle of the slice used for the MR imaging. Anterior (B) and posterior (C) to this plane the slices were divided in the midline. Samples 1 and 4 were used for density measurements. Samples 2, 5, and 6 were used for water content determination by wet-dry weight measurement. The left anterior cerebrum (sample 3) was fixed for histological examination. The dorsal cerebrum samples (1, 4, 5) include cerebral cortex and white matter superior to the roof of the lateral ventricle. Ventral sample 2 includes striatum and lateral cortex. Ventral sample 6 includes lateral cortex, anterior hippocampus, and thalamus. V = ventricle, H = hippocampus.