Corpus callosum (CC) is the primary fiber system bridging the cerebral hemispheres and is of critical importance for glioma migration which downgrades the prognosis. Here we present the specific pattern of CC restructuring in glioma patients. We probe that the magnetic resonance imaging-based fiber count decrease can be a ready noninvasive indicator of glioma aggressivity and prognosis. We find that to maintain the callosal neural transmission efficiency, the optimum architectural density of white matter fibers remains unchanged, even though there is gross fiber loss. This adaptation occurs by CC’s isotonic restructuration, a protective compensatory behavior for maintaining CC’s optimal functional efficiency despite malignant infiltration.

A comparative study was made on one Mysticete (the fin whale, Balaenoptera physalus) and one Odontocete species (the striped dolphin, Stenella coeruleoalba) by measuring several morphological characteristics seen in cross sections of the optic nerve. We found that the two cetacean nerves share a number of specializations that distinguish them from the optic nerve of terrestrial mammals. Fiber density is approximately two-fold lower than in land mammals. A corresponding increase in the cross-sectional area occupied by astrocytes is observed. A population of “giant” (up to 15 μm in diameter) optic axons is present in both the B. physalus and the S. coeruleoalba nerve. It is argued that these features probably reflect common adaptations to the constraints imposed by the aquatic environment. “Giant” optic axons might ensure short-latency detection of preys and other targets during navigation while the increased astroglial content might be related to the maintenance of neuronal function during periods of anaerobic metabolism under water.