Deafferentation-Induced Plasticity of Visual Callosal Connections: Predicting Critical Periods and Analyzing Cortical Abnormalities Using Diffusion Tensor Imaging

Figure 2

Comparing the arrangements of gyri, sulci, and visual areas in the unfolded and flattened cortex of ferrets and cats. Posterior is left, dorsal is up. (a) Intact right hemisphere of ferret brain showing the location of gyri, sulci and various cortical areas. Dashed lines indicate cuts made to separate the posterior block that was unfolded and flattened. (b) Diagram showing an unfolded and flattened ferret cortex. Curved arrows indicate further cuts made to fully flatten the cortex. Dashed lines indicate fundi of sulci, gray areas indicate the surface of gyri, large dotted line indicates the outline of V1, and lines made of small dots indicate the borders of other visual areas. These landmarks and lines are useful for correlating features of the callosal pattern to the patterns of gyri, sulci, and visual areas (see Figures 3(a), 3(b), and 3(c)). A: auditory cortex; as: ansate sulcus; ls: lateral sulcus; PPc: posterior parietal caudal; PPr: posterior parietal rostral; pss: pseudosylvian sulcus; S: somatosensory cortex; spl: splenial sulcus; sss: suprasylvian sulcus; SSY: suprasylvian visual area. (c) Schematic diagram of intact right hemisphere of cat brain showing location of various visual areas. Dashed line indicates lateral border of area 17. (d) Diagram showing an unfolded and flattened cat cortex. Curved arrows indicate cuts made to fully flatten the cortex. Dark and light areas correspond to gyri and sulci, respectively. Fine dashed lines indicate the lateral borders of areas 17 and 18. The heavy dashed line indicates the approximate location of several visual areas, including areas 18, 19, 20, 21, and suprasylvian areas. These lines are also useful for relating features of the callosal patterns to visual areas (see Figures 3(d), 3(e), and 3(f)). Unfolding and flattening the cortex of ferrets and cats were performed as described previously [7]. A: auditory cortex; S: somatosensory cortex; spl: splenial; lat: lateral; cru: cruciate; ssyl: suprasylvian. Scale bars = 1.0 cm. Adapted from Bock et al. [8]; Olavarria and Van Sluyters [9].