Deafferentation-Induced Plasticity of Visual Callosal Connections: Predicting Critical Periods and Analyzing Cortical Abnormalities Using Diffusion Tensor Imaging
Figure 6
Increased cerebral cortical diffusion anisotropy in the developing visual cortex accompanies reduction in the neuronal process orientation distribution width. (a, b) Golgi-stained visual cortex tissue visualized at 10x magnification from a P31 control (a) and BEP7 (b) ferret. Line segments (red) representing neuronal processes throughout a region of the cerebral cortex (corresponding to location 3 in (d)) are overlaid on (a), and on an image obtained from the same region of a BEP7 visual cortex at P31 in (b). The polar angle for each line segment was determined, and in (c), histograms representing the distribution of polar angles are shown for the control (black data points) and BEP7 (red data points) Golgi fields. (c) Solid lines represent the results of approximating the data points as a Von Mises distribution. The distribution observed for the BEP7 field is narrower, and hence characterized by a larger concentration parameter , than for the control. (d) Location of 5 other regions analyzed in control and BEP7 ferrets. Filled circles indicate fields obtained from coronal sections, and open circles from axial sections. Filled and open orange circles indicate the locations of nonvisual areas (n.v.). (e) Concentration parameters for the 5 other region of the visual cortex, obtained from pairs of coronal sections (solid bars in (e)) and axial sections (open bars in (e)). For all 5 visual regions, is larger for BEP7 animals (red solid and open bars) than for controls (black solid and open bars). For visual locations indicated with asterisks, 95% confidence intervals for BEP7 and control regions do not overlap [18]. Filled and open orange bars in (e) represent data analyzed for nonvisual regions of BEP7 cortices, while filled and open gray bars in e represent regions of nonvisual cortex in control cortices. Significant differences for nonvisual areas are not observed. Adapted from Bock et al. [18].
