Brain Connectivity and Brain Size

The mammalian brain varies in volume by five orders of magnitude. These size differences also affect the connectivity of the brain. In this article, we compare the cerebral and the cerebellar cortex in small and large brains. Both cortices show an almost proportionate increase in their surfaces with brain volume. However, there are fundamental differences in the structure between the two, such as the isotropic connectivity of the cerebral as opposed to the anisotropic connectivity of the cerebellar cortex and the self-connectedness on the cerebral as opposed to the feed-forward connectivity on the cerebellar cortex. These differences are also reflected in different scaling factors with brain size.