This just in... "Researchers who transplanted human brain cells into newborn mice said the rodents grew up to be smarter than their normal littermates, learning how to associate a tone with an electric shock more quickly and finding escape hatches faster," according to research published March 7 in the journal Cell Stem Cell. "The experiments are aimed at making models to study human brain diseases such as Huntington's and schizophrenia, as well as nerve diseases such as multiple sclerosis." However, "the team at the University of Rochester say their findings also suggest that these brain cells, called glial cells, may very well be one of the important factors that make humans different from other animals." In a Guest Blog entry for Scientific American (3/8), R. Douglas Fields, an expert on neuron-glia interactions, brain development, and the cellular mechanisms of memory, writes, "The researchers observed that human astrocytes were 20 times larger in volume than rodent astrocytes. This was far greater than the proportionate increase in size of human neurons relative to rodent neurons." Study co-author Steven Goldman, MD, PhD, an expert in the field of neural stem cells, explained, "Human astrocytes are larger and more varied in morphology, features that accompanied evolution of the human brain." True story. FYI, astrocytes are the "support" cells in the brain that surround the neurons (nerve cells) in the brain and provide the background matrix that makes up the brain. They are also the main source of brain tumors. In fact, tumors of neuron cells almost do not exist, but tumors of astrocytes are a major cause of death, accounting for the vast majority of fatal "brain tumors".