Massive whale brains: smaller corpus callosum, more glial cells

[extherian]

This article on the brains of dolphins and whales indicates that the corpus callosum hardly changes in size even with the largest brains. On the other hand, the ratio of glial cells to neurons increases enormously, negating much of the benefit of their larger brain size. Communication between neocortical neurons becomes much more difficult with increasing brain size, but not necessarily communication between different brain hemispheres.